Soft soil press-in type lateral pressure instrument
By designing a soft-soil press-in side pressure meter, using composite adhesive film and sensors to directly measure expansion deformation and water pressure, the existing side pressure meter has solved the problems of drilling disturbance and inaccurate measurement in soft-soil test, and achieved high-precision and low-cost soft-soil testing.
Patent Information
- Application Number
- CN202422144780.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2025-07-18
- Estimated Expiration
- 2034-09-02
AI Technical Summary
In soft soil testing, the existing side pressure instruments have problems such as drilling disturbance, complex structure, difficult operation, high testing cost, and inaccurate measurement of pressure and bulk variables. Especially when the depth is large, the data reading delay cannot meet the accuracy requirements.
A soft soil press-in side pressure meter is designed, including a mandrel, a composite adhesive film, a water stop adhesive ring, annular blade foot, a displacement arm sensor and a water pressure sensor. The probe is sent to a predetermined depth by static pressure or hammering, and the expansion deformation and water pressure are directly measured using the composite adhesive film and sensor to avoid drilling disturbances and improve measurement accuracy.
It realizes high accuracy and low cost of soft soil testing, avoids drilling disturbances, can directly measure the true characteristic parameters of the soil, simplifies the operation process, and reduces the testing cost.
Smart Images
Figure CN223119131U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of in-situ testing of geotechnical engineering, in particular to a soft soil pressure-injected dilatometer. Background Technique
[0002] The dilatometer test is one of the most widely used testing methods in in-situ testing of geotechnical engineering because of its wide applicable strata and unrestricted test depth. The principle of the dilatometer test is to apply a uniform circumferential pressure to the dilatometer probe by a pressure source, which indirectly acts on the soil mass, causing the surrounding soil mass to produce a cylindrical expansion deformation. According to the relationship between soil pressure and deformation, the strength and deformation parameters of the foundation soil are obtained.
[0003] According to the type of hole formation, the dilatometer can be divided into a pre-bored dilatometer and a self-boring dilatometer. The pre-bored dilatometer is applicable to clay, silt, sand, gravel, residual soil, weathered rock, soft rock, etc. whose hole walls can maintain self-stability. The self-boring dilatometer is applicable to clay, silt, sand, and saturated soft soil whose hole walls cannot self-stabilize. The existing dilatometers mainly have the following problems in soft soil testing:
[0004] (1) The pre-bored dilatometer uses a geological drill to pre-drill a hole. Affected by the hole formation accuracy of the geological drill, it is extremely easy to cause inestimable effects such as softening, shrinkage, and even collapse of the test hole wall during the dilatometer test in soft soil.
[0005] (2) The self-boring dilatometer uses a cutter installed at the bottom of the dilatometer probe to fully stir the soil mass, and then brings the soil chips back to the ground through mud circulation. However, the self-boring dilatometer has a complex structure, high operation difficulty, and high test cost.
[0006] (3) The calibration pressure of the rubber membrane used in the conventional dilatometer probe is 2-3 bar. The test pressure in soft soil is relatively small, often only 3-10 bar. The calibration pressure accounts for a relatively large proportion, and the result analysis is extremely easy to be distorted. The dilatometer test in soft soil requires a relatively large volume change compared with other types of soil dilatometer tests. The existing rubber membrane has a small volume change, and the obtained P-Y curve of the dilatometer test is often incomplete. There are large errors in extending the P-Y curve by the curve fitting method.
[0007] (4) The conventional dilatometer test measures the pressure and volume change of the dilatometer probe through the pressure gauge and water column on the dilatometer, which cannot accurately reflect the pressure and volume change inside the dilatometer probe. Especially when the test depth is relatively large, there is a pressure lag effect, and the data reading is delayed, which cannot meet the high-precision requirements of soft soil testing. Content of the Utility Model
[0008] In view of this, the present utility model provides a soft soil press-in type dilatometer, which can adapt to soft soil strata that cannot self-stabilize, can directly statically press or hammer the dilatometer probe to a predetermined test depth, avoids the problem of drilling disturbance of soft soil, and can accurately measure the expansion deformation and water pressure, thereby obtaining more real undisturbed soft soil dilatation characteristic parameters.
[0009] To achieve the above object, the technical solution provided by the present utility model is as follows:
[0010] A soft soil press-in type dilatometer includes a dilatometer probe, a loading control system, and a data acquisition system. The dilatometer probe includes a mandrel, a composite rubber membrane, a water stop rubber ring, an annular cutting edge, a displacement arm sensor, and a water pressure sensor. The inner side wall of the mandrel has a water inlet hole and a drainage hole, and the upper end of the mandrel has a pressure relief hole; the composite rubber membrane is wound around the outer wall of the mandrel, and water stop rubber rings are provided between the upper and lower ends of the mandrel and the composite rubber membrane; the annular cutting edge is fixed to the bottom of the mandrel and forms a soil inlet cavity with the inner cavity of the mandrel; the displacement arm sensor and the water pressure sensor are fixed on the mandrel; the loading control system is connected to the water inlet hole through a pipeline; the data acquisition system is connected to the displacement arm sensor and the water pressure sensor through a data line in the drainage hole. The displacement arm sensor is used to monitor the change of displacement data, and the water pressure sensor is used to monitor the change of water pressure data.
[0011] Further, the upper and lower ends of the composite rubber membrane are respectively arranged on the outer wall of the mandrel through pressure rings, and two limiting rings are fixed at both ends of the mandrel and are tightly pressed with the pressure rings; the water stop rubber ring, the mandrel, the pressure ring, and the composite rubber membrane form a measurement cavity.
[0012] Further, the cutting edge angle of the annular cutting edge faces inwards, and the inner cavity volume from the annular cutting edge to the pressure relief hole is not less than the outer volume between the two limiting rings.
[0013] Further, it includes six displacement arm sensors, and the six displacement arm sensors are equidistantly and symmetrically fixed on the mandrel, and the data lines connected to the displacement arm sensors pass through the drainage hole and are connected to the data acquisition system.
[0014] Further, it includes one water pressure sensor, and the water pressure sensor is fixed in the middle of the mandrel, and the data line connected to the displacement arm sensor passes through the drainage hole and is connected to the data acquisition system.
[0015] The beneficial effects of the soft soil press-in type dilatometer provided by the present utility model are as follows:
[0016] 1. Referring to the thin-wall soil sampler or the ring cutter, the inner cavity of the probe mandrel and the annular cutting edge form a soil inlet cavity. The annular cutting edge is in the inner side soil squeezing mode, and the soil column outside the end of the probe is accommodated through the inner cavity of the probe. The contact form between the outer side and the soil is similar to that between the thin-wall soil sampler or the ring cutter and the soil, mainly vertical end sliding friction, and there is no artificial diameter expansion in the normal direction. Thus, when the probe is statically pressed or hammered into soft soil, the soft soil can be squeezed into the soil inlet cavity, avoiding artificial extrusion of the soil in the test section and ensuring the original state of the soft soil outside the probe.
[0017] 2. The push-in type pressuremeter probe is sent to the predetermined test depth by static pressure or hammering, which is simple to operate, has low test cost.
[0018] 3. By using a composite rubber membrane, the pressure during the pressure rate calibration of the probe is significantly reduced, and the expansion amount of the circumferential deformation of the probe is greatly increased, better adapting to the large deformation characteristics of soft soil, and avoiding over-consumption in the initial stage of the limited range and being unable to measure the complete pressuremeter curve; the maximum circumferential deformation can reach 5 cm, and the ultimate pressure P of the soil mass can be directly measured. L
[0019] 4. Through the displacement arm sensor and water pressure sensor arranged in the probe, the expansion deformation of the composite rubber membrane and the water pressure in the probe can be directly measured, avoiding the influence of pressure lag, compensating for the accuracy error problem of the single-chamber pressuremeter test, and greatly improving the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components.
[0021] Figure 1 FIG. is a schematic structural diagram of a push-in type pressuremeter for soft soil provided by an embodiment of the present invention;
[0022] Figure 2 is Figure 1 the sectional view at the A-A position of
[0023] Figure 3 is Figure 1 the sectional view at the B-B position of
[0024] Figure 4 is Figure 1 the partial enlarged view at the C position of
[0025] Figure 5 is the result of the pressuremeter model test completed by the Menard G-AM type pressuremeter;
[0026] Figure 6 The results of a pressuremeter model test completed by a soft soil pressuremeter provided by an embodiment of the present utility model.
[0027] Explanation of reference numerals:
[0028] 1 - mandrel, 2 - water inlet hole, 3 - drainage hole, 4 - pressure relief hole, 5 - composite rubber film, 6 - pressure ring, 7 - limit ring, 8 - water stop rubber ring, 9 - annular cutting edge, 10 - displacement arm sensor, 11 - water pressure sensor, 12 - loading control system, 13 - data acquisition system. Specific embodiments
[0029] To further elaborate on the technical means and effects adopted by the present utility model to achieve the intended utility model purpose, the following combines the accompanying drawings and preferred embodiments to detail the specific embodiments, structures, features, and effects of a soft soil pressuremeter proposed according to the present utility model. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any form.
[0030] The term "and / or" in this article is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B is specifically understood as: A and B can be included simultaneously, A can exist alone, or B can exist alone, and any of the above three situations can be satisfied.
[0031] See Figures 1 to 4 , a soft soil pressuremeter provided by an embodiment of the present utility model includes a pressuremeter probe, a loading control system 12, and a data acquisition system 13. The pressuremeter probe includes a mandrel 1, a water inlet hole 2, a drainage hole 3, a pressure relief hole 4, a composite rubber film 5, a pressure ring 6, a limit ring 7, a water stop rubber ring 8, an annular cutting edge 9, a displacement arm sensor 10, and a water pressure sensor 11.
[0032] The side wall interior of the mandrel 1 has a water inlet hole 2 and a drainage hole 3; the upper end of the mandrel 1 has a pressure relief hole 4; the upper and lower ends of the composite rubber film 5 are arranged on the mandrel 1 through a pressure ring 6; two limit rings 8 are fixed at both ends of the mandrel 1 and are tightly pressed with the pressure ring 6; the water stop rubber ring 7 is located at both ends of the mandrel 1, between the mandrel 1 and the composite rubber film 5, and forms a measurement chamber with the mandrel 1, the pressure ring 6, and the composite rubber film 5; the annular cutting edge 9 is fixed at the bottom of the mandrel 1 and forms an earth inlet chamber with the inner cavity of the mandrel 1; the displacement arm sensor 10 and the water pressure sensor 11 are fixed on the mandrel 1; the loading control system 12 is connected to the water inlet hole 2 through a pipeline; the data acquisition system 13 is connected to the displacement arm sensor 10 and the water pressure sensor 11 through a data line in the drainage hole 3.
[0033] Among them, the inner side wall of the mandrel 1 is provided with the water inlet hole 2 and the drain hole 3. In this case, it is avoided that the pipeline of the traditional pressuremeter probe is arranged inside the probe, which hinders the smoothness of the soil inlet cavity; arranging the water inlet hole 2 and the drain hole 3 inside the side wall of the mandrel 1 can ensure the integrity of the pipeline without damage during the process of the probe being statically pressed or hammered into soft soil.
[0034] Among them, the upper end of the mandrel 1 is provided with a pressure relief hole 4. In this case, it can avoid the air compression inside the probe during the process of the probe being statically pressed or hammered into soft soil.
[0035] Among them, the upper and lower ends of the composite rubber film 5 are arranged on the mandrel 1 through the pressure ring 6; the two limiting rings 8 are fixed at both ends of the mandrel 1 and are tightly pressed with the pressure ring 6. In this case, the stability of both ends of the composite rubber film 5 is ensured, and the shedding of the composite rubber film during the test can be avoided.
[0036] Among them, the water stop rubber ring 7 is located at the upper and lower ends of the mandrel 1, between the mandrel 1 and the composite rubber film 5, and forms a measurement cavity with the mandrel 1, the pressure ring 6 and the composite rubber film 5. In this case, the sealing effect of the measurement cavity is further enhanced, the pressure loss caused by water leakage is avoided, and the measurement accuracy of pressure and volume can be effectively improved.
[0037] Among them, the annular cutting edge 9 is fixed at the bottom of the mandrel 1 and forms a soil inlet cavity with the inner cavity of the mandrel 1. In this case, during the process of the probe being statically pressed or hammered into soft soil, the annular cutting edge cuts the soft soil at the bottom of the probe, so that the soft soil can be extruded into the soil inlet cavity, and the inner column of soil at the inner side of the probe end is eliminated through the inner cavity of the probe. The contact form with the soil on the outside is similar to the contact form between a thin-wall soil sampler or a ring knife and the soil, mainly vertical end sliding friction, and there is no artificial diameter expansion in the normal direction, avoiding the artificial extrusion of the soil in the test section and ensuring the original state of the soil outside the probe.
[0038] Among them, the displacement arm sensor 10 and the water pressure sensor 11 are fixed on the mandrel 1. In this case, the expansion deformation of the composite rubber film 5 and the water pressure inside the probe can be directly measured, avoiding the influence of pressure lag, compensating for the precision error problem of the single-chamber pressuremeter test, and greatly improving the test precision.
[0039] Among them, the data acquisition system 13 is connected to the displacement arm sensor 10 and the water pressure sensor 11 through the data line in the drain hole 3. In this case, the multi-purpose use of a single hole of the probe drain hole is realized, avoiding the reduction of the overall stiffness caused by too many holes in the probe, and ensuring that the probe will not bend and deform during the process of being statically pressed or hammered into soft soil.
[0040] Using the utility model to conduct a soft soil press-in type pressuremeter test includes the following steps:
[0041] Step S1: Connect the loading control system 12, data acquisition system 13 and the pressuremeter probe. Conduct the calibration of the binding force rate and comprehensive deformation rate of the composite film 5 for the pressuremeter probe.
[0042] Step S2: Hydrostatically press or hammer the pressuremeter probe into the predetermined test depth of the soft soil, and record the test depth and the groundwater level. Determine whether the soft soil is disturbed according to the change of the displacement data monitored by the displacement arm sensor 9, and determine the magnitude of the initial pressure inside the pressuremeter probe according to the change of the water pressure data monitored by the water pressure sensor 10.
[0043] Step S3: Estimate the test load and load it in 8 - 10 levels. Then conduct the first - stage test loading, and record the data of the probe volume change, displacement arm sensor and water pressure sensor at 15s, 30s, 60s, 120s, 180s after the completion of the first - stage pressure loading.
[0044] Step S4: After reaching the predetermined steady - pressure time, conduct the second - stage test loading, and repeat the above steps until the test ends.
[0045] Step S5: Immediately after the test ends, relieve the pressure and return the water to the pressuremeter probe. Wait for 2 - 3 minutes after the data of the loading control system, displacement arm sensor and water pressure sensor are stable, and then take out the pressuremeter probe.
[0046] The beneficial effects of the present utility model are as follows:
[0047] 1. Referring to the thin - wall soil sampler or the ring knife, the inner cavity of the probe mandrel and the annular cutting edge form an earth - entering cavity. The annular cutting edge is in the inner - side soil - squeezing mode. The soil column outside the end of the probe is accommodated through the inner cavity of the probe. The contact form between the outside and the soil is similar to the contact form between the thin - wall soil sampler or the ring knife and the soil, mainly the vertical end - sliding friction, and there is no artificial diameter - expanding effect in the normal direction. It ensures that during the process of hydrostatically pressing or hammering the probe into the soft soil, the soft soil can be squeezed into the earth - entering cavity, avoiding the artificial extrusion of the soil in the test section and ensuring the original state of the soft soil outside the probe.
[0048] 2. Send the pressure - type pressuremeter probe to the predetermined test depth by hydrostatic pressure or hammering, which is simple to operate and has a low test cost.
[0049] 3. By changing to the composite film, the pressure during the pressure calibration of the probe is significantly reduced, and the expansion amount of the circumferential deformation of the probe is greatly increased, better adapting to the large - deformation characteristics of the soft soil, avoiding the excessive consumption of the limited range in the initial stage and being unable to measure the complete pressuremeter curve. The maximum circumferential deformation can reach 5 cm, and the ultimate pressure P of the soil mass can be directly measured. L 。
[0050] 4. By arranging a displacement arm sensor and a water pressure sensor inside the probe, the expansion deformation of the composite film and the water pressure inside the probe can be directly measured, avoiding the influence of pressure lag, compensating for the accuracy error problem of the single-chamber pressuremeter test, and greatly improving the test accuracy.
[0051] Application example: Pressuremeter test on soft muddy soil
[0052] A certain soft muddy silty clay, after being remolded in a 1m×1m×1m model box indoors, the water content is obtained as 44.4% through indoor geotechnical tests on the sampled soil, the wet density is 1.84 g / cm 3 , the void ratio is 1.139; the cohesion is 10.23 kPa, the internal friction angle is 7.2°, the undrained shear strength obtained from the vane shear test is 28.6 kPa, and the compression modulus is 3.012 MPa. Comparative tests are respectively carried out using the most common Menard G-AM type pressuremeter and the soft soil press-in type pressuremeter proposed by the present utility model, and the results are shown in Table 1.
[0053] Table 1 Comparison table of tests with different pressuremeters
[0054]
[0055] Where K is the safety factor, and K = 2.0 is taken.
[0056] The pressuremeter model test is completed using the Menard G-AM type pressuremeter, and it adopts the method of manually forming a hole and lowering the pressuremeter probe. The test results are as Figure 5 shown. Affected by the volume change limit, the maximum test volume change is 660 cm 3 , and the pressuremeter limit pressure P L = 212 kPa is obtained after the pressuremeter curve is extended.
[0057] The pressuremeter model test is completed using the soft soil press-in type pressuremeter provided by the embodiment of the present utility model, and the pressuremeter probe is directly pressed into the model test box. The test results are as Figure 6 shown. The maximum test volume change is 5996 cm 3 , and the pressuremeter curve already shows an asymptote parallel to the V axis.
[0058] From Figure 5 and Figure 6 comparison, it can be seen that the soft soil press-in type pressuremeter provided by the present utility model has less disturbance to the soil body, and the obtained pressuremeter modulus E M is higher than the test result of the Menard pressuremeter, and the characteristic value of the pressuremeter bearing capacity calculated using P f -P0 is also higher; on the contrary, using (P LThe characteristic value of the lateral pressure bearing capacity calculated by (-P0) / K is slightly lower. This is because the test curve of the conventional Menard pressuremeter needs to be extended, which is affected by a large amount of human factors. The measured curve can more truly reflect the actual state of the soil mass.
[0059] This example preferably realizes the test results of a push-in type pressuremeter for soft soil described in the present utility model in a soft soil stratum, and fully demonstrates the application results of the core innovation (push-in type pressuremeter) of the present utility model.
[0060] Compared with the conventional Menard G-AM type pressuremeter that requires pre-boring, in addition to using a push-in type pressure probe, the present utility model also integrates a water pressure sensor and a displacement arm sensor in the probe. Compared with the conventional method of reading with a pressure gauge and a water level pipe, the accuracy of the test data is greatly improved.
[0061] Although the preferred embodiments of the present utility model have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present utility model.
[0062] Obviously, those skilled in the art can make various changes and modifications to the present utility model without departing from the spirit and scope of the present utility model. Thus, if these modifications and variations of the present utility model fall within the scope of the claims of the present utility model and their equivalent technologies, the present utility model also intends to include these modifications and variations.
Claims
1. A soft soil pressure-injected dilatometer, characterized in that, It includes a pressuremeter probe, a loading control system, and a data acquisition system. The pressuremeter probe includes a mandrel, a composite rubber membrane, a water-stop rubber ring, an annular cutting edge, a displacement arm sensor, and a water pressure sensor. There are water inlet holes and drain holes inside the side wall of the mandrel, and a pressure relief hole is provided at the upper end of the mandrel; the composite rubber membrane is wound around the outer wall of the mandrel, and water-stop rubber rings are provided between the upper and lower ends of the mandrel and the composite rubber membrane; the annular cutting edge is fixed to the bottom of the mandrel, forming a soil inlet cavity with the inner cavity of the mandrel; the displacement arm sensor and the water pressure sensor are fixed on the mandrel; the loading control system is connected to the water inlet hole through a pipeline; the data acquisition system is connected to the displacement arm sensor and the water pressure sensor through data lines in the drain hole. The displacement arm sensor is used to monitor the change of displacement data, and the water pressure sensor is used to monitor the change of water pressure data.
2. The pressuremeter for soft soil by pressure injection according to claim 1, characterized in that, The upper and lower ends of the composite rubber membrane are respectively arranged on the outer wall of the mandrel through pressure rings, and two limit rings are fixed at both ends of the mandrel and are pressed tightly with the pressure rings; the water-stop rubber ring forms a measurement cavity with the mandrel, the pressure ring and the composite rubber membrane.
3. The pressuremeter by press-in type for soft soil according to claim 1, wherein, The cutting edge of the annular cutting edge faces inwards, and the inner cavity volume from the annular cutting edge to the pressure relief hole is not less than the outer volume between the two limit rings.
4. A pressuremeter for soft soil by press-in type according to claim 1, characterized in that, It includes six displacement arm sensors. The six displacement arm sensors are fixed on the mandrel at equal intervals and symmetrically, and the data lines connected to the displacement arm sensors pass through the drain hole and are connected to the data acquisition system.
5. The pressuremeter by press-in type for soft soil according to claim 1, wherein, It includes a water pressure sensor. The water pressure sensor is fixed in the middle of the mandrel, and the data line connected to the displacement arm sensor passes through the drain hole and is connected to the data acquisition system.