An integrated device for measuring pore water pressure in soft soil and a construction method

Abstract

The invention discloses an integrated device for measuring pore water pressure in soft soil, and discloses a construction method for measuring pore water pressure in soft soil. The integrated device includes a cone head, a plurality of measuring components and a plurality of isolation components, and the measuring components and the isolation components are arranged at intervals from bottom to top; the measuring component includes a pore water pressure gauge and a measuring tube body, and the pore water pressure gauge is used to monitor the pore water pressure at the position where the measuring tube body is located, and the lower end of the measuring tube body is detachably connected to the cone head; the upper end of the measuring tube body is detachably connected to the lower end of the sealing tube body of the isolation component, and the upper end of the sealing tube body is detachably connected to the lower end of another measuring tube body, and the upper end of the uppermost sealing tube body can be used to connect with external equipment. The integrated device can measure the pore water pressure at different elevations at the same time by pressing into the soil layer once, and the construction is convenient and simple to operate. The cone head, the measuring component and the isolation component are recyclable, which reduces the construction cost.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to an integrated device for measuring pore water pressure in soft soil and a construction method. Background Art

[0002] In traditional pore water pressure measurements, usually one pore water pressure gauge is buried in one hole. When multiple pore water pressure gauges are to be buried at different depths in the same hole, it is necessary to use dry soil balls or expansive mature soil to strictly isolate the pore water pressure gauges from each other to avoid the penetration of the pore water pressures of the upper and lower layers. Otherwise, the purpose of measuring the changes in pore water pressure at each depth of the soil layer cannot be achieved. Existing burial methods for pore water pressure gauges include drilling and pressing. The drilling method is to first drill a hole with a drilling rig, and then place the pore water pressure gauge at the designed elevation, which is suitable for all kinds of soil layers. However, in the drilling method, it is difficult to seal the hole between the upper and lower pore water pressure gauges, and the hole is sealed by relying on water-isolating materials such as bentonite mud balls or by pulling out the pipe to collapse the hole. In the former, the bentonite mud ball is usually unable to sink to the designed isolation position due to the shrinkage of the pores. The latter has a poor sealing effect and generally fails to meet the monitoring requirements. The press-in burial is to press the pore water pressure gauge directly into the predetermined depth. It has a fast construction speed and low cost and is suitable for soft soil layers. However, this method is usually only applicable to burying a pore water pressure gauge in a plane position.

[0003] The existing burial method of pore water pressure gauge has many defects:

[0004] Pore ​​water pressure gauges cannot be reused. Regardless of whether they are buried by drilling or direct pressing, due to the large burial depth, pore water pressure gauges are generally left in the soil and not recovered.

[0005] The survival rate of pore water pressure gauges is low. In soft soil areas, when the pore water pressure gauge and the conductor directly rub against the existing soil when buried by direct pressure, it is easy to cause the conductor to break or damage the pore water pressure gauge. When the drilling method is used, the hole is usually protected with a casing, and the casing is pulled out after the pore water pressure gauge is installed in place. However, when the pore water pressure gauge is lowered and the casing is pulled out, the cable is easily damaged.

[0006] Excess pore water pressure dissipates slowly and the waiting time for measurement is long. For soft soils such as silt and silt, the permeability coefficient is low, and it is easy to press into the buried method and cause a large excess pore water pressure that cannot be dissipated in time, and even exceed the range of the pore water pressure meter, causing equipment damage. Therefore, it can only be inserted intermittently, and after it is fully inserted, it is necessary to wait for the excess pore water pressure generated during the burial process to basically dissipate before formal measurement can be made. For soft soils with low permeability coefficients and deep burial depths of pore water pressure meters, it takes days or even months for the excess pore water pressure to dissipate, which is also difficult to adapt to projects with tight schedules.

[0007] Mud and sand can easily enter the device and damage the pore water pressure meter or affect the normal operation of the pore water pressure meter. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an integrated device for measuring pore water pressure in soft soil, which is easy to construct and has a fast construction speed, reduces the risk of mud and sand entering the interior of the device, and can be reused.

[0009] The present invention also provides a construction method for measuring pore water pressure in the soft soil.

[0010] According to the first aspect of the present invention, an integrated device for measuring pore water pressure in soft soil comprises a cone head, a plurality of measuring components and a plurality of isolation components, wherein the measuring components and the isolation components are arranged in a spaced manner from bottom to top;

[0011] A piezoresistive hydraulic sensor is provided in the cone head, and a water-permeable member is provided on the side wall of the cone head. The water-permeable member is used to allow pore water outside the cone head to flow to the piezoresistive hydraulic sensor. The piezoresistive hydraulic sensor is used to monitor the dissipation of excess pore water pressure at the cone head in real time.

[0012] The measuring assembly comprises a pore water pressure gauge, a measuring tube body, a first water-gas pipe and a circulation device, the first water-gas pipe is provided with a branch pipe, the branch pipe is provided with an electromagnetic valve and the circulation device, the circulation device is annular and sleeved on the first water-gas pipe, a plurality of channels of the circulation device are radially distributed to spray air / water or extract air / water to the peripheral wall of the measuring tube body, the electromagnetic valve is used to open and close the circulation device, the first water-gas pipe, the pore water pressure gauge and the circulation device are all arranged in the measuring tube body, a plurality of connecting holes are opened on the outer wall of the measuring tube body, the measuring tube body is provided with a first filter layer in the area corresponding to the connecting holes, the first filter layer is used to filter mud and sand passing through the connecting holes to isolate the mud and sand outside the measuring tube body, the connecting holes, the circulation device and the first water-gas pipe are used to pass water or air in turn, the pore water pressure gauge is used to monitor the pore water pressure at the position where the measuring tube body is located, and the lower end of the measuring tube body is detachably connected to the cone head;

[0013] The isolation assembly includes a sealed tube body, a second water-gas pipe and two partition plates, the two partition plates respectively seal the two ends of the sealed tube body, the second water-gas pipe runs through the two partition plates, the upper end of the measuring tube body is detachably connected to the lower end of the sealed tube body, the lower end of the second water-gas pipe is detachably connected to the upper end of the first water-gas pipe, the upper end of the sealed tube body is used for detachably connecting to the lower end of another measuring tube body, the upper end of the topmost sealed tube body can be used for connecting to an external device, the upper end of the second water-gas pipe is used for detachably connecting to the lower end of the first water-gas pipe of another measuring tube body, the upper end of the second water-gas pipe is used for detachably connecting to a water-gas power device, and the water-gas power device is used for pumping air / water or extracting air / water.

[0014] At least the following beneficial effects are achieved:

[0015] When it is necessary to measure the pore water pressure in soft soil, according to the soil layer and the measurement requirements at different elevations, select the appropriate number of measuring components and the appropriate number of isolation components, and set the isolation components of different lengths according to the actual situation, so that each measuring component is at a different elevation. After the integrated device for measuring pore water pressure in soft soil is pressed into the soil layer, the pore water pressure at different elevations can be monitored simultaneously, which can effectively improve the construction and measurement efficiency, and the operation method is simple. The integrated device for measuring pore water pressure in soft soil can be pulled out of the soil layer, and the cone head and the measuring component, as well as the measuring component and the isolation component are connected in a detachable manner, so the cone head, the measuring component and the isolation component can be recycled, reducing the construction cost. The setting of the first filter layer can reduce the risk of mud and sand in the soil layer entering the measuring tube body through the connecting hole, thereby reducing the risk of damage to the pore water pressure gauge, and reducing the risk of blocking the circulation device, branch pipe, solenoid valve, first water and gas pipe and second water and gas pipe.

[0016] According to some embodiments of the present invention, the pore water pressure gauge is coated with a second filter layer to isolate the mud and sand outside the pore water pressure gauge.

[0017] According to some embodiments of the present invention, the structure of the second filter layer includes a cloth bag and a water-permeable material disposed in the cloth bag, and the pore water pressure gauge is coated in the water-permeable material.

[0018] According to some embodiments of the present invention, the flow device is coated with a third filter layer.

[0019] According to some embodiments of the present invention, the cone head and the measuring tube body, as well as the measuring tube body and the sealing tube body are connected via fasteners.

[0020] According to some embodiments of the present invention, the measuring tube body includes two half shells opened in half.

[0021] According to some embodiments of the present invention, a receiving groove is opened on the conical surface of the cone head, the piezoresistive hydraulic sensor is arranged in the receiving groove, and the permeable member is a permeable stone, and the permeable stone is arranged at the notch of the receiving groove.

[0022] According to some embodiments of the present invention, a bus interface is provided in the measuring tube body, the piezoresistive hydraulic sensor is electrically connected to the bus interface via a first cable, the pore water pressure meter is electrically connected to the bus interface via a second cable, the bus interface is connected to a bus, the bus is connected to a data acquisition instrument, and the data acquisition instrument is electrically connected to a data processing device.

[0023] According to some embodiments of the present invention, the control line of the solenoid valve is electrically connected to the bus interface, a wire hole is provided on the sealing tube body, the inner cavity of the measuring tube body and the wire hole are used for the bus to pass through, and a sealant is provided between the inner wall of the wire hole and the bus.

[0024] A construction method for measuring pore water pressure in soft soil according to an embodiment of the second aspect of the present invention includes the following steps.

[0025] Assembly of the integrated device for measuring pore water pressure in soft soil: determine the burial depth, vertical spacing and number of pore water pressure gauges, then select the number of cone heads, measuring components and isolation components, pre-saturate the indoor air of the pore water pressure gauges to be installed, and complete the assembly of cone heads, measuring components and isolation components on the ground;

[0026] Pressing the integrated device for measuring pore water pressure in soft soil: The integrated device for measuring pore water pressure in soft soil is pressed into the soil layer to be measured at a certain rate using a pressing device. During the pressing process, the solenoid valve is opened to read the pore water pressure meter data U Ji , U Ji is the i-th pore pressure value, so that the connecting hole, the flow device, the first water-air pipe and the second water-air pipe are connected to form a channel, so that the excess pore water generated by the integrated device for measuring pore water pressure in soft soil during the process of pressing into the soil layer is discharged from the soil layer through the channel, thereby accelerating the rapid dissipation of the excess pore water pressure. Specifically, when U Ji ≤U Jicr When U Jicris the critical value of the i-th pore pressure value, that is, when any of the pore water pressure gauges accumulates to the critical value, the rate of pressing into the soil layer is reduced or water is pumped through the channel to force the pore water pressure to be reduced. The rate of pressing into the soil layer and the pumping power are dynamically adjusted with the pore water pressure gauge. By monitoring the dissipation law of excess pore water pressure, the rate of pressing into the soil layer and the pumping power are dynamically adjusted until the integrated device for measuring pore water pressure in soft soil reaches the target depth position. If the connecting hole is blocked by mud and sand, resulting in slow dissipation of excess pore water pressure, pumping is stopped, and water or air is pumped into the channel to flush out the mud and sand blocking the connecting hole to keep the connecting hole smooth;

[0027] Waiting for the excess pore water pressure to dissipate: After the integrated device for measuring pore water pressure in soft soil is pressed to the target depth, the total pore water pressure value U at different times t is monitored by the piezoresistive hydraulic sensor. d , excess pore water pressure U=U d -γ w h, and get the Ut curve, where γ w is the gravity of water, h is the vertical distance between the cone head and the groundwater level;

[0028] If U>U r According to the excess pore water pressure values ​​at two moments in the Ut curve, the following formula is used to estimate the time from U down to U r Time required r , Where U r is the maximum excess pore water pressure allowed to remain in the soil when the excess pore water pressure has basically dissipated. U1 and U2 are the excess pore water pressures at time t1 and time t2, respectively. The dissipation time of the excess pore water pressure is based on the initial zero time when the cone head is pressed into the target depth.

[0029] If r <t p , t p is the waiting time allowed for engineering monitoring after the cone head is pressed in. The pore water pressure can be measured formally after the excess pore water pressure dissipates. Otherwise, t r >t p , it means that the waiting time is too long. At this time, pumping should be continued to speed up the dissipation of excess pore water pressure until U r , formula derivation: (t r Derivation, according to the dissipation law formula of excess pore water pressure: Thus we can deduce: And then launched This transformation gives

[0030] ​Pore ​​water pressure measurement: When the excess pore water pressure dissipates to the required level U r After the pressure drops below 100°, stop pumping, close the solenoid valve, and wait for the pore water pressure gauge reading to stabilize. Then record the initial value U of each pore water pressure gauge. Ji0 , start pore water pressure measurement;

[0031] Pulling out and cleaning the integrated device for measuring pore water pressure in soft soil: Pulling out the integrated device for measuring pore water pressure in soft soil from the soil layer and laying it flat on the ground, then opening the solenoid valve, pumping water into the channel to clean the mud and sand remaining in the measuring tube body, the circulation device, the first water-air pipe and the second water-air pipe, and then pumping air into the channel to empty the water in the measuring tube body, the circulation device, the first water-air pipe and the second water-air pipe;

[0032] Disassembling the integrated device for measuring pore water pressure in soft soil: disassembling the cone head, the measuring component and the isolation component to recycle and use the cone head, the measuring component and the isolation component.

[0033] At least the following beneficial effects are achieved:

[0034] A construction method for measuring pore water pressure in soft soil has all the beneficial effects brought by the integrated device for measuring pore water pressure in soft soil in the above-mentioned embodiment, and will not be repeated here.

[0035] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0037] Figure 1 This is a schematic structural diagram of an integrated device for measuring pore water pressure in soft soil according to an embodiment of the present invention;

[0038] Figure 2 for Figure 1 A local enlarged schematic diagram of the middle A;

[0039] Figure 3 for Figure 1 A partial enlarged schematic diagram of point B in the middle;

[0040] Figure 4 This is a schematic structural diagram of an integrated device for measuring pore water pressure in soft soil according to another embodiment of the present invention;

[0041] Figure 5 It is a schematic cross-sectional structure diagram of a measuring tube body in an integrated device for measuring pore water pressure in soft soil according to an embodiment of the present invention;

[0042] Figure 6 is the Ut curve;

[0043] Figure Number:

[0044] Cone head 100, piezoresistive hydraulic sensor 110, storage groove 120, permeable member 130, measuring assembly 200, pore water pressure gauge 210, second filter layer 211, measuring tube body 220, connecting hole 221, first water and gas pipe 230, circulation device 240, isolation assembly 300, sealing tube body 310, second water and gas pipe 320, partition plate 330, solenoid valve 400, fastener 500, bus 600, bus interface 700. DETAILED DESCRIPTION

[0045] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0046] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0047] In the description of the present invention, "a plurality" means more than two. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0048] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0049] Reference Figure 1 , Figure 2 and Figure 4 The present invention discloses an integrated device for measuring pore water pressure in soft soil, comprising a cone head 100, a plurality of measuring components 200 and a plurality of isolation components 300, wherein the measuring components 200 and the isolation components 300 are arranged in an interval from bottom to top;

[0050] A piezoresistive hydraulic sensor 110 is provided in the cone head 100, and a water-permeable member 130 is provided on the side wall of the cone head 100. The water-permeable member 130 is used to allow pore water outside the cone head 100 to flow to the piezoresistive hydraulic sensor 110. The piezoresistive hydraulic sensor 110 is used to monitor the dissipation of excess pore water pressure at the cone head 100 in real time.

[0051] The measuring assembly 200 includes a pore water pressure gauge 210, a measuring tube body 220, a first water-gas pipe 230 and a circulation device 240. The first water-gas pipe 230 is provided with a branch pipe, and the branch pipe is provided with an electromagnetic valve 400 and a circulation device 240. The circulation device 240 is annular and sleeved on the first water-gas pipe 230. The plurality of holes of the circulation device 240 are radially distributed to spray air / water or extract air / water to the peripheral wall of the measuring tube body 220. The electromagnetic valve 400 is used to open and close the circulation device 240. The first water-gas pipe 230, the pore water pressure gauge 210 and the circulation device 240 are all provided with a branch pipe. In the measuring tube body 220, a plurality of connecting holes 221 are provided on the outer wall of the measuring tube body 220. The measuring tube body 220 is provided with a first filter layer (not shown in the figure) in the area corresponding to the connecting holes 221. The first filter layer is used to filter mud and sand passing through the connecting holes 221 to isolate the mud and sand outside the measuring tube body 220. The connecting holes 221, the flow device 240 and the first water-gas pipe 230 are used to pass water or ventilation in sequence. The pore water pressure gauge 210 is used to monitor the pore water pressure at the location of the measuring tube body 220. The lower end of the measuring tube body 220 is detachably connected to the cone head 100.

[0052] The isolation assembly 300 includes a sealed tube body 310, a second water-gas pipe 320 and two partition plates 330. The two partition plates 330 respectively seal the two ends of the sealed tube body 310. The second water-gas pipe 320 runs through the two partition plates 330. The upper end of the measuring tube body 220 is detachably connected to the lower end of the sealed tube body 310, the lower end of the second water-gas pipe 320 is detachably connected to the upper end of the first water-gas pipe 230, the upper end of the sealed tube body 310 is used to be detachably connected to the lower end of another measuring tube body 220, the upper end of the uppermost sealed tube body 310 can be used to connect to an external device, the upper end of the second water-gas pipe 320 is used to be detachably connected to the lower end of the first water-gas pipe 230 of another measuring tube body 220, and the upper end of the uppermost second water-gas pipe 320 is used to be detachably connected to a water-gas power device, which is used to pump air / water or extract air / water.

[0053] When it is necessary to measure the pore water pressure in soft soil, a suitable number of measuring components 200 and a suitable number of isolation components 300 are selected according to the soil layer and the measurement requirements at different elevations. Several measuring components 200 and several isolation components 300 are arranged at intervals from bottom to top, and the cone head 100 is connected to the lower end of the lowest measuring component 200, thereby obtaining the required integrated device for measuring the pore water pressure in soft soil.

[0054] It is understandable that the external device connection can be a press-in device, which is used to press the integrated device for measuring pore water pressure in soft soil into the soil layer; the external device connection can also be a pull-out device, which is used to pull the integrated device for measuring pore water pressure in soft soil out of the soil layer. Press-in devices and pull-out devices are common devices on the market and will not be redundantly introduced here.

[0055] When the integrated device for measuring pore water pressure in soft soil is pressed into the soil layer, when the soil layer outside the cone head 100 has pore water, the pore water passes through the water-permeable member 130 and contacts the piezoresistive hydraulic sensor 110 in the cone head 100, and the piezoresistive hydraulic sensor 110 is immersed in the pore water. The piezoresistive hydraulic sensor 110 can dynamically monitor the pore water pressure at the location of the cone head 100. The piezoresistive hydraulic sensor 110 has the characteristic of high sensitivity.

[0056] The isolation component 300 has the function of isolating the two measuring components 200. The uppermost isolation component 300 is used to connect with an external pressing device or a pulling device. The pressing device can be used to press the integrated device for measuring pore water pressure in soft soil into the soil layer where the pore water pressure needs to be monitored, and the pulling device can be used to pull the integrated device for measuring pore water pressure in soft soil out of the soil layer.

[0057] The cone head 100 and the measuring assembly 200 as well as the measuring assembly 200 and the isolation assembly 300 are connected in a detachable manner. The number of the measuring assemblies 200 and the isolation assembly 300 can be selected according to actual needs, and the isolation assemblies 300 of different lengths can be set according to actual conditions, so that each measuring assembly 200 is at a different elevation. The pore water at the corresponding different elevations enters the measuring tube body 220 through the connecting holes 221 on each measuring tube body 220 and contacts the pore water pressure gauge 210. The pore water pressure gauge 210 of each measuring assembly 200 is immersed in the pore water at different elevations. After the excess pore water pressure generated by the integrated device for measuring pore water pressure in soft soil being pressed into the soil layer is basically dissipated, each pore water pressure gauge 210 can monitor the pore water pressure at the position of different measuring tube bodies 220, that is, the pore water pressure at different elevations can be monitored simultaneously. The integrated device for measuring pore water pressure in soft soil is pressed into the soil layer once to measure the pore water pressure at several elevations, which can effectively improve the construction and measurement efficiency and has a simple operation method.

[0058] When the electromagnetic valve 400 is closed, the isolation assembly 300 does not have a conducting function between two adjacent measuring assemblies 200, thereby preventing pore water at different elevations from penetrating and improving the accuracy of pore water pressure measurement.

[0059] A plurality of first water-gas pipes 230 and a plurality of second water-gas pipes 320 are connected at intervals from bottom to top, and all first water-gas pipes 230 are connected with a flow device 240, which is arranged in the measuring tube body 220. The upper end of the second water-gas pipe 320 at the top is used to be detachably connected to a water-gas power device, and the water-gas power device is used to pump air / water or extract air / water. By extracting the water and / or gas entering the measuring tube body 220 through the water-gas power device, the second water-gas pipe 320, the first water-gas pipe 230 and the flow device 240, the excess pore water pressure can be dissipated faster, and the pore water pressure at different elevations can be detected in a timely manner, thereby improving the efficiency of detecting the pore water pressure. Gas and / or water are pumped into the measuring tube body 220 through the water-gas power device, the second water-gas pipe 320, the first water-gas pipe 230 and the circulation device 240, and the gas and / or water are discharged to the outside of the measuring tube body 220 through the connecting hole 221, thereby preventing and clearing the connecting hole 221.

[0060] Since the first water-gas pipe 230 is provided with a branch pipe, and the branch pipe is provided with an electromagnetic valve 400 and a circulation device 240, the electromagnetic valve 400 is used to open and close the circulation device 240, and the first water-gas pipe 230 and the circulation device 240 are both arranged in the measuring tube body 220, so the opening and closing of the circulation devices 240 in different measuring components 200 can be controlled by controlling different electromagnetic valves 400, so as to pump air / water or exhaust air / water to the measuring components 200 at different elevations, thereby accelerating the dissipation of the excess pore water pressure of the outer soil wall of the measuring components 200 at different elevations, or preventing and clearing the blockage of the connecting holes 221 of the measuring components 200 at different elevations.

[0061] The first filter layer can reduce the risk of mud and sand in the soil layer entering the measuring tube body 220 through the connecting hole 221, thereby reducing the risk of damage to the pore water pressure gauge 210, and reducing the risk of blockage of the circulation device 240, the branch pipe, the solenoid valve 400, the first water and air pipe 230, and the second water and air pipe 320. It can be understood that the first filter layer is cylindrical and abuts against the inner wall of the measuring tube body 220.

[0062] The water-gas power device includes a high-pressure water supply system, a pumping system and a high-pressure gas supply system. The high-pressure water supply system is used to transport high-pressure water into the measuring tube body 220, the pumping system is used to pump out the pore water in the measuring tube body 220, and the high-pressure gas supply system is used to transport high-pressure gas into the measuring tube body 220. The pressure of high-pressure water can reach 10.0MPa and above. The pressure of high-pressure gas can reach 6.3MPa and above. The high-pressure water supply system, the pumping system and the high-pressure gas supply system can all use common equipment on the market, and no redundant introduction is made here.

[0063] The integrated device for measuring pore water pressure in soft soil can be pulled out from the soil layer by a pulling-out device. The cone head 100 and the measuring component 200 as well as the measuring component 200 and the isolation component 300 are connected in a detachable manner, which facilitates the maintenance and replacement of the cone head 100, the measuring component 200 and the isolation component 300. The cone head 100, the measuring component 200 and the isolation component 300 can all be recycled, thereby reducing the construction cost.

[0064] In summary, the integrated device for measuring pore water pressure in soft soil has the following advantages:

[0065] ①. By pressing the integrated device for measuring pore water pressure in soft soil into the soil layer, the pore water pressure at different elevations can be measured simultaneously, realizing rapid and synchronous measurement of multiple targets, with less construction workload, simple construction method and high construction efficiency.

[0066] ②, the water-gas power device, the second water-gas pipe 320, the first water-gas pipe 230, the branch pipe, the electromagnetic valve 400 and the circulation device 240 can pump out the pore water, accelerate the dissipation of the excess pore water pressure, and improve the efficiency of the pore water pressure measurement in the soft soil; the water-gas power device, the second water-gas pipe 320, the first water-gas pipe 230, the branch pipe, the electromagnetic valve 400 and the circulation device 240 can pump water or gas to the measuring tube body 220 to avoid the connecting hole 221 from being blocked, and the second water-gas pipe 320, the first water-gas pipe 230, the branch pipe, the electromagnetic valve 400, the circulation device 240 and the measuring tube body 220 have a self-cleaning function;

[0067] ③. The isolation component 300 separates two adjacent measuring components 200, effectively reducing the risk of pore water channeling at different elevations. Compared with the traditional partition method, the construction requirements will be lower, the anti-channeling effect will be better, and the reliability will be higher;

[0068] ④. The cone head 100, the measuring assembly 200 and the isolation assembly 300 can be disassembled, which is convenient for the maintenance, replacement and recycling of the cone head 100, the measuring assembly 200 and the isolation assembly 300, thereby reducing the construction cost.

[0069] In this embodiment, there are two measuring components 200 and two isolating components 300. The cone head 100, one measuring component 200, one isolating component 300, another measuring component 200 and another isolating component 300 are detachably connected in sequence from bottom to top, and the upper end of the uppermost isolating component 300 can be used to connect to an external device.

[0070] The second water and gas pipe 320 passes through the upper and lower ends of the sealed tube body 310, that is, the second water and gas pipe 320 passes through the two partition plates 330 on the sealed tube body 310, and the second water and gas pipe 320 is sealedly connected to the first water and gas pipe 230 to avoid water leakage and air leakage between the second water and gas pipe 320 and the first water and gas pipe 230. The partition plate 330 is provided with an avoidance hole for the second water and gas pipe 320 to pass through, and the second water and gas pipe 320 is sealedly connected to the inner wall of the avoidance hole to avoid water leakage or air leakage between the second water and gas pipe 320 and the partition plate 330.

[0071] It is understandable that the structure of the flow device 240 in the bottom measuring component 200 may be different from that of the flow devices 240 in other measuring components 200. The flow device 240 in the bottom measuring component 200 may be directly connected to the lower end of the first water and gas pipe 230, and the solenoid valve 400 is disposed on the first water and gas pipe 230. All flow devices 240 have a plurality of channels, and the plurality of channels are disposed around the outer shell of the flow device 240, and the plurality of channels are radially distributed, so that water / gas can reach most or all of the connecting holes 221 on the measuring tube body 220 through the plurality of channels, thereby clearing most or all of the connecting holes 221 on the measuring tube body 220.

[0072] See also Figure 4 In another embodiment, the number of the cone head 100, the measuring component 200 and the isolation component 300 is one each, and the cone head 100, the measuring component 200 and the isolation component 300 are detachably connected in sequence from bottom to top, and the upper end of the uppermost isolation component 300 can be used to connect to an external device.

[0073] See also Figure 1 In some of the embodiments, the pore water pressure gauge 210 is coated with a second filter layer 211 , and the second filter layer 211 further isolates mud and sand outside the pore water pressure gauge 210 to ensure the normal operation of the pore water pressure gauge 210 .

[0074] In some embodiments, the structure of the second filter layer 211 includes a cloth bag and a water-permeable material disposed in the cloth bag, the pore water pressure gauge 210 is coated in the water-permeable material, and the cloth bag plays the role of wrapping the water-permeable material and the pore water pressure gauge 210. The water-permeable material is a common material on the market, and no redundant introduction is made here.

[0075] The circulation device 240 is coated with a third filter layer (not shown in the figure), which can further prevent foreign matter such as mud and sand from entering the circulation device 240, the branch pipe and the first water-gas pipe 230, thereby preventing the branch pipe, the first water-gas pipe 230, the second water-gas pipe 320 and the water-gas power device from being blocked and damaged.

[0076] The circulation device 240 is essentially a water distributor, and the outer circumferential surface of the circulation device 240 has a plurality of channels. The circulation device 240, the pore water pressure gauge 210, the piezoresistive hydraulic pressure sensor 110 and the solenoid valve 400 are all common components in the market, and no redundant introduction is given here.

[0077] See also Figure 3 In some embodiments, the cone head 100 and the measuring tube body 220 as well as the measuring tube body 220 and the sealing tube body 310 are connected by fasteners 500, and the fasteners 500 can achieve quick connection and disassembly. The fasteners 500 can be bolts, screws or screws.

[0078] An inner flange is provided on the inner edge of the end face of the measuring tube body 220, and an outer flange is provided on the outer edge of the end face of the sealing tube body 310, the outer flange wraps the inner flange, and the outer flange and the inner flange are sealed and connected; or an outer flange is provided on the outer edge of the end face of the measuring tube body 220, and an inner flange is provided on the inner edge of the end face of the sealing tube body 310, the outer flange wraps the inner flange, and the outer flange and the inner flange are tightly fitted and connected. The outer flange and the inner flange can make the integrated device for measuring pore water pressure in soft soil more resistant to bending as a whole. A connecting hole and a threaded hole are provided on the outer flange and the inner flange, respectively, and the threaded section of the fastener 500 passes through the connecting hole and is threadedly connected to the inner wall of the threaded hole.

[0079] See also Figure 5 In some embodiments, the measuring tube body 220 includes two half shells that are opened in half, and the two half shells are assembled into the measuring tube body 220. A guide groove and a guide rail are respectively provided on the two planes of the half shells, and the length direction of the guide groove and the guide rail is parallel to the length direction of the half shells. The guide groove on one half shell cooperates with the guide rail on the other half shell, and the guide rail on one half shell cooperates with the guide groove on the other half shell, so as to ensure the accuracy of splicing the two half shells. Furthermore, the width of the inside of the guide groove is greater than the width of the notch of the guide groove, and the shape of the guide rail cooperates with the internal space of the guide groove. After the guide rail is inserted into the guide groove, the two half shells cannot be directly separated, thereby improving the connection effect and structural strength of the two half shells.

[0080] Of course, the two half shells can be connected by welding. The measuring tube body 220 can also be made in an integrally formed manner.

[0081] See also Figure 1 In some of the embodiments, a receiving groove 120 is opened on the conical surface of the cone head 100, and the piezoresistive hydraulic sensor 110 is arranged in the receiving groove 120. The permeable member 130 is a permeable stone, and the permeable stone is arranged at the notch of the receiving groove 120. The permeable member 130 can allow water to penetrate into the receiving groove 120 and prevent mud and sand from entering the receiving groove 120, so that the piezoresistive hydraulic sensor 110 can be submerged in water without being damaged by mud and sand, and the piezoresistive hydraulic sensor 110 can measure the pore water pressure.

[0082] In some of the embodiments, a bus interface 700 is provided in the measuring tube body 220, the piezoresistive hydraulic sensor 110 is electrically connected to the bus interface 700 via a first cable, the pore water pressure meter 210 is electrically connected to the bus interface 700 via a second cable, the bus interface 700 is connected to the bus 600, the bus 600 is connected to a data acquisition instrument, and the data acquisition instrument is electrically connected to a data processing device.

[0083] In some embodiments, the control line of the solenoid valve 400 is electrically connected to the bus interface 700, the bus 600 is electrically connected to the controller, and the controller controls the opening and closing of the solenoid valve 400. The data processing device receives and displays the measurement results of the piezoresistive hydraulic sensor 110 and the pore water pressure gauge 210, and the data processing device can control the opening and closing of the solenoid valve 400.

[0084] The sealing tube body 310 is provided with a wire hole, and the inner cavity of the measuring tube body 220 and the wire hole are used for the bus 600 to pass through. A sealant is provided between the inner wall of the wire hole and the bus 600. The first cable, the second cable and the control line are all arranged on the inner wall of the measuring tube body 220 and the sealing tube body 310, reducing the risk of the first cable, the second cable and the control line being worn and broken. The bus interface 700 and the bus 600 are arranged to facilitate the rapid electrical connection of each piezoresistive hydraulic sensor 110, each pore water pressure gauge 210 and the data processing device, or the rapid electrical disconnection of each piezoresistive hydraulic sensor 110, each pore water pressure gauge 210 and the data processing device.

[0085] It is conceivable that the bus 600 and the inner wall of the wire hole can be sealed by sealing glue. The bus 600 is a wire harness. One end of the bus 600 has a plurality of first terminals, and the other end of the bus 600 has a plurality of second terminals, and the plurality of first terminals correspond to the plurality of second terminals one by one. The bus 600 is a common component on the market.

[0086] The invention also discloses a construction method for measuring pore water pressure in soft soil, which comprises the following steps.

[0087] Assembly of the integrated device for measuring pore water pressure in soft soil: determine the buried depth, vertical spacing and number of pore water pressure gauges 210, then select the number of cone heads 100, measuring components 200 and isolation components 300, pre-saturate the indoor air of the pore water pressure gauges 210 to be installed, and complete the assembly of the cone heads 100, measuring components 200 and isolation components 300 on the ground;

[0088] Pressing the integrated device for measuring pore water pressure in soft soil: The integrated device for measuring pore water pressure in soft soil is pressed into the soil layer to be measured at a certain rate by using the pressing device. During the pressing process, the electromagnetic valve 400 is opened to read the data U of the pore water pressure meter 210. Ji , U Ji is the i-th pore pressure value, so that the connecting hole 221, the flow device 240, the first water-gas pipe 230 and the second water-gas pipe 320 are connected to form a channel, so that the excess pore water generated by the integrated device for measuring pore water pressure in soft soil during the process of pressing into the soil layer is discharged from the soil layer through the channel, thereby accelerating the rapid dissipation of the excess pore water pressure. Specifically, when U Ji ≤U Jicr When U Jicr is the critical value of the i-th pore pressure value, that is, when any pore water pressure gauge 210 accumulates to the critical value, the rate of pressing into the soil layer is reduced or water is pumped through the channel to force the pore water pressure to be reduced. The rate of pressing into the soil layer and the pumping power are dynamically adjusted with the pore water pressure gauge 210. By monitoring the dissipation law of the excess pore water pressure, the rate of pressing into the soil layer and the pumping power are dynamically adjusted until the integrated device for measuring pore water pressure in soft soil reaches the target depth position. If the connecting hole 221 is blocked by mud and sand, resulting in slow dissipation of the excess pore water pressure, pumping is stopped, and water or air is pumped into the channel to flush out the mud and sand blocking the connecting hole 221 to keep the connecting hole 221 smooth;

[0089] Waiting for the excess pore water pressure to dissipate: After the integrated device for measuring pore water pressure in soft soil is pressed to the target depth, the total pore water pressure value U at different times t is monitored by the piezoresistive hydraulic sensor 110. d , excess pore water pressure U=U d -γ w h, and get the Ut curve, such as Figure 6 , where γ w is the gravity of water, h is the vertical distance between the cone head 100 and the groundwater level;

[0090] If U>U r According to the excess pore water pressure values ​​at two moments in the Ut curve, the following formula is used to estimate the time from U down to U r Time required r , Where U r It is the maximum excess pore water pressure allowed to remain in the soil when the excess pore water pressure has basically dissipated. U1 and U2 are the excess pore water pressures at time t1 and time t2, respectively. The dissipation time of the excess pore water pressure is based on the initial zero time when the cone head is pressed into the target depth by 100.

[0091] If r <t p , tp is the waiting time allowed for engineering monitoring after the cone head 100 is pressed in. The pore water pressure can be measured formally after the excess pore water pressure dissipates. Otherwise, t r >t p , it means that the waiting time is too long. At this time, pumping should be continued to accelerate the dissipation of excess pore water pressure until U<U r , formula derivation: (t r Derivation, according to the dissipation law formula of excess pore water pressure: Thus we can deduce: And then launched This transformation gives

[0092] Pore ​​water pressure measurement: When the excess pore water pressure dissipates to the required level U r After the pressure drops below 0.1, stop pumping, close the electromagnetic valve 400, and wait for the pore water pressure gauge 210 reading to stabilize, and then record the initial value U of each pore water pressure gauge 210. Ji0 , start pore water pressure measurement;

[0093] Pull out and clean the integrated device for measuring pore water pressure in soft soil: pull out the integrated device for measuring pore water pressure in soft soil from the soil layer and lay it flat on the ground, then open the solenoid valve 400, pump water into the channel to clean the mud and sand remaining in the measuring tube body 220, the circulation device 240, the first water-gas pipe 230 and the second water-gas pipe 320, and then pump air into the channel to empty the water in the measuring tube body 220, the circulation device 240, the first water-gas pipe 230 and the second water-gas pipe 320;

[0094] Disassembling the integrated device for measuring pore water pressure in soft soil: disassembling the cone head 100, the measuring assembly 200 and the isolation assembly 300 to recycle and use the cone head 100, the measuring assembly 200 and the isolation assembly 300.

[0095] It should be understood that the construction method for measuring pore water pressure in soft soil adopts the above-mentioned integrated device for measuring pore water pressure in soft soil.

[0096] The construction method for measuring pore water pressure in soft soil has all the beneficial effects brought by the integrated device for measuring pore water pressure in soft soil in the above-mentioned embodiment, and will not be described again here.

[0097] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art may make equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An integrated device for measuring pore water pressure in soft soil, characterized in that: include: A cone head (100), a plurality of measuring components (200) and a plurality of isolation components (300), wherein the measuring components (200) and the isolation components (300) are arranged in an interval from bottom to top; A piezoresistive hydraulic sensor (110) is provided in the cone head (100), and a water-permeable member (130) is provided on the side wall of the cone head (100). The water-permeable member (130) is used to allow pore water outside the cone head (100) to flow to the piezoresistive hydraulic sensor (110). The piezoresistive hydraulic sensor (110) is used to monitor the dissipation of excess pore water pressure at the cone head (100) in real time. The measuring assembly (200) comprises a pore water pressure gauge (210), a measuring tube body (220), a first water-gas pipe (230) and a circulation device (240); the first water-gas pipe (230) is provided with a branch pipe; the branch pipe is provided with an electromagnetic valve (400) and the circulation device (240); the circulation device (240) is annular and sleeved on the first water-gas pipe (230); a plurality of holes of the circulation device (240) are radially distributed to spray air / water or extract air / water to the peripheral wall of the measuring tube body (220); the electromagnetic valve (400) is used to open and close the circulation device (240); the first water-gas pipe (230), the pore water pressure gauge (210) and the circulation device (240) are connected to the pore water pressure gauge (210) and the circulation device (240); 0) are arranged in the measuring tube body (220), a plurality of communicating holes (221) are opened on the outer wall of the measuring tube body (220), the measuring tube body (220) is provided with a first filter layer in the area corresponding to the communicating holes (221), the first filter layer is used to filter mud and sand passing through the communicating holes (221), so as to isolate the mud and sand outside the measuring tube body (220), the communicating holes (221), the flow device (240) and the first water-gas pipe (230) are used to pass water or air in sequence, the pore water pressure gauge (210) is used to monitor the pore water pressure at the position where the measuring tube body (220) is located, and the lower end of the measuring tube body (220) is detachably connected to the cone head (100); The isolation assembly (300) comprises a sealed tube body (310), a second water-gas pipe (320) and two partition plates (330), wherein the two partition plates (330) respectively seal two ends of the sealed tube body (310), the second water-gas pipe (320) passes through the two partition plates (330), the upper end of the measuring tube body (220) is detachably connected to the lower end of the sealed tube body (310), the lower end of the second water-gas pipe (320) is detachably connected to the upper end of the first water-gas pipe (230), and the The upper end of the sealed tube body (310) is used to be detachably connected to the lower end of another measuring tube body (220), the upper end of the uppermost sealed tube body (310) can be used to connect to an external device, the upper end of the second water-gas pipe (320) is used to be detachably connected to the lower end of the first water-gas pipe (230) of another measuring tube body (220), and the upper end of the uppermost second water-gas pipe (320) is used to be detachably connected to a water-gas power device, and the water-gas power device is used to pump air / water or extract air / water.

2. The integrated device for measuring pore water pressure in soft soil according to claim 1, characterized in that: The pore water pressure gauge (210) is coated with a second filter layer (211) to isolate the mud and sand outside the pore water pressure gauge (210).

3. The integrated device for measuring pore water pressure in soft soil according to claim 2, characterized in that: The structure of the second filter layer (211) comprises a cloth bag and a water-permeable material arranged in the cloth bag, and the pore water pressure gauge (210) is coated in the water-permeable material.

4. The integrated device for measuring pore water pressure in soft soil according to claim 1, characterized in that: The circulation device (240) is coated with a third filter layer.

5. The integrated device for measuring pore water pressure in soft soil according to claim 1, characterized in that: The cone head (100) and the measuring tube body (220), as well as the measuring tube body (220) and the sealing tube body (310) are all connected via fasteners (500).

6. The integrated device for measuring pore water pressure in soft soil according to claim 1, characterized in that: The measuring tube body (220) comprises two half shells which are split in half.

7. The integrated device for measuring pore water pressure in soft soil according to claim 1, characterized in that: A receiving groove (120) is provided on the conical surface of the cone head (100), the piezoresistive hydraulic pressure sensor (110) is arranged in the receiving groove (120), and the water-permeable member (130) is a water-permeable stone, which is arranged at the notch of the receiving groove (120).

8. The integrated device for measuring pore water pressure in soft soil according to claim 1, characterized in that: A bus interface (700) is provided in the measuring tube body (220); the piezoresistive hydraulic sensor (110) is electrically connected to the bus interface (700) via a first cable; the pore water pressure gauge (210) is electrically connected to the bus interface (700) via a second cable; the bus interface (700) is connected to a bus (600); the bus (600) is connected to a data acquisition instrument; and the data acquisition instrument is electrically connected to a data processing device.

9. The integrated device for measuring pore water pressure in soft soil according to claim 8, characterized in that: The control line of the solenoid valve (400) is electrically connected to the bus interface (700); a wire hole is provided on the sealing tube body (310); the inner cavity of the measuring tube body (220) and the wire hole are used for the bus (600) to pass through; and a sealant is provided between the inner wall of the wire hole and the bus (600).

10. A construction method for measuring pore water pressure in soft soil, using the integrated device for measuring pore water pressure in soft soil according to any one of claims 1 to 9, characterized in that: The following steps are included: Assembly of an integrated device for measuring pore water pressure in soft soil: determining the buried depth, vertical spacing and number of pore water pressure gauges (210), then selecting the number of cone heads (100), measuring components (200) and isolation components (300), pre-saturating the indoor air of the pore water pressure gauges (210) to be installed, and completing the assembly of the cone heads (100), measuring components (200) and isolation components (300) on the ground; Pressing the integrated device for measuring pore water pressure in soft soil into the soil layer to be measured at a certain rate using a pressing device. During the pressing process, the electromagnetic valve (400) is opened to read the data of the pore water pressure meter (210). , is the i-th pore pressure value, so that the connecting hole (221), the flow device (240), the first water-gas pipe (230) and the second water-gas pipe (320) are connected to form a channel, so that the excess pore water generated by the integrated device for measuring pore water pressure in soft soil during the process of being pressed into the soil layer is discharged from the soil layer through the channel, thereby accelerating the rapid dissipation of the excess pore water pressure. Specifically, when ≤ hour, is the critical value of the i-th pore pressure value, that is, when any of the pore water pressure gauges (210) accumulates to the critical value, the rate of pressing into the soil layer is reduced or water is pumped through the channel to force the pore water pressure to be reduced. The rate of pressing into the soil layer and the pumping power are dynamically adjusted with the pore water pressure gauge (210). By monitoring the dissipation law of the excess pore water pressure, the rate of pressing into the soil layer and the pumping power are dynamically adjusted until the integrated device for measuring pore water pressure in soft soil reaches the target depth position. If the connecting hole (221) is blocked by mud and sand, resulting in slow dissipation of the excess pore water pressure, pumping is stopped, and water or air is pumped into the channel to flush out the mud and sand blocking the connecting hole (221) to keep the connecting hole (221) unobstructed; Waiting for the excess pore water pressure to dissipate: After the integrated device for measuring pore water pressure in soft soil is pressed into the target depth, the total pore water pressure value at different times t is monitored by the piezoresistive hydraulic sensor (110) Excess pore water pressure = - h, get -t curve, where is the gravity of water, and h is the vertical distance between the cone head (100) and the groundwater level; like > According to the excess pore water pressure values ​​at two moments in the Ut curve, the following formula is used to estimate the time when U is reduced to Time required , , where It is the maximum excess pore water pressure allowed to remain in the soil when the excess pore water pressure has basically dissipated. and They are Moment and The excess pore water pressure at the time, and the dissipation time of the excess pore water pressure are both based on the initial zero time when the cone head (100) is pressed into the target depth; like < , The waiting time allowed by engineering monitoring after the cone head (100) is pressed in is the waiting time allowed by engineering monitoring. The pore water pressure is measured after the excess pore water pressure dissipates. Otherwise, > , it means that the waiting time is too long. At this time, pumping should be continued to speed up the dissipation of excess pore water pressure until < , formula derivation: Derivation, according to the dissipation law formula of excess pore water pressure: , thus we can deduce: ; , this formula is transformed into + ; Pore ​​water pressure measurement: When the excess pore water pressure dissipates to the required level After the above, the pumping is stopped, the electromagnetic valve (400) is closed, and after the reading of the pore water pressure gauge (210) is stabilized, the initial value of each pore water pressure gauge (210) is recorded. , start pore water pressure measurement; Pulling out and cleaning the integrated device for measuring pore water pressure in soft soil: pulling out the integrated device for measuring pore water pressure in soft soil from the soil layer and placing it flat on the ground, then opening the solenoid valve (400) and pumping water into the channel to clean the mud and sand remaining in the measuring tube body (220), the circulation device (240), the first water-air pipe (230) and the second water-air pipe (320), and then pumping air into the channel to empty the water in the measuring tube body (220), the circulation device (240), the first water-air pipe (230) and the second water-air pipe (320); Disassembling the integrated device for measuring pore water pressure in soft soil: disassembling the cone head (100), the measuring component (200) and the isolation component (300) to recycle and use the cone head (100), the measuring component (200) and the isolation component (300).

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