Method for sinking a caisson in a high-water mucky ground

Abstract

The high water level silt foundation soil inner spiral flow well sinking method belongs to the sinking well construction field, and aims to guarantee sinking well construction quality, spiral flow well safety and protection effect. The method comprises the following steps: 1, construction preparation; 2, construction of water-resisting curtain, the water-resisting curtain is a combined water-resisting curtain, comprising mixing piles and Larsen steel sheet piles arranged around the spiral flow well, the depth of the mixing piles is greater than the design depth of the spiral flow well, and before the mixing piles are completely cemented and solidified, the Larsen steel sheet piles are pressed into the formed mixing piles one by one, so that the Larsen steel sheet piles straddle the construction joints of the mixing piles and are integrated with the mixing piles; 3, cylinder sinking operation of the spiral flow well; and 4, bottom sealing of the spiral flow well. The mixing piles and the Larsen steel sheet piles are combined to form a closed water-resisting curtain, the lateral stiffness and waterproof performance of the water-resisting curtain are improved, good water-resisting effect, guiding effect and safety protection effect are achieved, and sliding and deviation in the water-rich silt foundation are avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of sinking well construction, and particularly relates to a method for sinking a spiral-flow well in a high-water mucky foundation soil. BACKGROUND

[0002] In the field of metallurgical industrial engineering, a turbid circulating water system is usually used to accelerate the cleaning of industrial waste residues of iron oxide scale of a hot rolling production line, and the deslagging wastewater is collected from a deslagging ditch and then flows into a spiral-flow sedimentation tank, in which the larger-density sand particles and waste residues mixed in the wastewater are discharged under the action of vortex sedimentation and centrifugal rotation, the iron oxide residues are then grabbed by a bridge-type grab crane, and finally the water is pumped out by a circulating pump for recycling.

[0003] At present, the spiral-flow sedimentation tank is usually constructed by means of large excavation, reverse construction, underground continuous wall and sinking well, etc.; among them, the sinking well process is widely used in practical engineering due to the characteristics of smaller land occupation, stronger applicability to narrow and limited space, relatively simple construction method and smaller influence on the surrounding construction environment. However, considering the difficulty in process control of sinking well operation, the difficulty in prediction of adverse influence of hydrogeological environment and the uncontrollable influence factors of safety and quality technical parameters, there are still many problems to be solved in practical engineering application. Among them, the sinking well operation in high-water mucky foundation soil is a relatively typical engineering case, which has the following problems:

[0004] Firstly, due to the limited amount of sinking well dewatering in high-water mucky foundation, the groundwater recharge speed of mucky foundation is relatively fast, which leads to long-term lowering of groundwater level and overlong dewatering period, thereby restricting the construction progress on site; and the over-dense arrangement of dewatering wells around is not economical, occupies too large site area and affects other engineering construction due to site limitation.

[0005] Secondly, during the sinking well process of taking soil in the spiral-flow well cylinder in mucky foundation soil, the three-way stress state of the original foundation soil is changed, which makes it prone to water and mud gushing, quicksand and other geological disasters under the lateral pressure of surrounding soil, greatly increases the workload and construction cost of taking soil in the cylinder, and has great safety and quality risks.

[0006] Thirdly, in the sinking well in mucky soft foundation soil, the spiral-flow well cylinder is prone to tilting or deviation due to the influence of uneven construction load and slippage effect in the mucky layer, so as to fail to meet the construction precision and quality requirements of the spiral-flow well cylinder.

[0007] The high-water mucky geology refers to the geology affected by underground water.

[0008] Due to the above factors, the sinking well of spiral-flow well has safety and quality risks such as slippage, cylinder tilting or deviation, which is not conducive to the sinking well of spiral-flow well. SUMMARY

[0009] The application aims to solve the problem of high safety risk of slippage, inclination or deviation of the cylinder of a caisson in a high-water-level silt geological foundation, and provides a high-water-level silt geological foundation caisson sinking method, which ensures the construction quality, safety and protection of the caisson.

[0010] The technical scheme of the application is as follows: a high-water-level silt geological foundation caisson sinking method, comprising the following steps:

[0011] Step 1: site leveling, construction preparation, measurement positioning and establishment of a control axis network;

[0012] Step 2: construction of a water-resisting curtain, the water-resisting curtain is a combined water-resisting curtain, comprising mixing piles and Larsen steel sheet piles arranged around the caisson, the depth of the mixing piles is greater than the design depth of the caisson, and the Larsen steel sheet piles are pressed into the formed mixing piles one by one before the mixing piles are completely cemented and solidified, so that the Larsen steel sheet piles straddle the construction joints of the mixing piles and are integrated with the mixing piles;

[0013] Before the mixing piles are initially hardened, a multi-hole detection guide pipe is pressed into the mixing piles, the multi-hole detection guide pipe is located on the inner side of the Larsen steel sheet pile, and a detection meter is inserted into the multi-hole detection guide pipe for detection;

[0014] Step 3: sinking operation of the cylinder of the caisson;

[0015] Step 4: caisson bottom sealing and bottom plate construction; the multi-hole detection guide pipe is filled.

[0016] Further, the multi-hole detection guide pipe comprises a pipe body and a guide head at the bottom end of the pipe body; the guide head is a solid cone that gradually decreases in size from one end adjacent to the pipe body to the bottom end in the axial direction; and the pipe body is provided with a plurality of fine-mesh penetration holes.

[0017] Further, a protective cap is detachably connected to the top end of the pipe body, and a through hole is formed in the protective cap for the detection meter to pass through and detect.

[0018] Further, the multi-hole detection guide pipe is divided into several pipe segments, and the pipe segments are pressed into the mixing piles in the form of a butt joint; a pressure plate is detachably installed at the top end of each pipe segment when the pipe segment is pressed in; and the pressure plate comprises a plate body and a plug-in connector arranged at the center of the bottom surface of the plate body, and the plug-in connector is matched with the inner cavity of the pipe segment.

[0019] Further, in step 4, self-compacting fine-stone micro-expansion concrete with a height of one grade higher than the cylinder wall of the caisson is poured into the multi-hole detection guide pipe, and the self-compacting fine-stone micro-expansion concrete penetrates from the fine-mesh penetration holes distributed on the wall of the multi-hole detection guide pipe and tightly engages with the mixing piles.

[0020] The beneficial effects of the present application are: the high water level silt foundation soil inner spiral flow well sinking method disclosed by the present application adopts the combination of the mixing pile and the Larsen steel sheet pile to form a closed water-resisting curtain, which significantly improves the lateral stiffness and waterproof performance, and plays a good water-resisting effect, guiding effect and safety protection effect.

[0021] The combined water-resisting curtain of the preceding construction plays a good guiding effect and isolation protection effect on the inner spiral flow well sinking operation, avoids the sliding and deviation in the water-rich silt foundation, and at the same time, the good isolation effect formed can also reduce the adverse effects of the sinking operation on the surrounding environment, such as the foundation soil sliding and uneven settlement, so that the construction in the limited construction site is more adaptable and operable.

[0022] The deep mixing pile and the Larsen steel sheet pile can be constructed synchronously in front and back, which greatly shortens the construction period; and before the complete initial setting and hardening, the real-time detection of the groundwater level and the water-resisting effect during the sinking operation is carried out through the pre-buried solid front cone multi-hole detection guide pipe, so as to ensure the construction quality and safety reliability of the spiral flow well sinking operation. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a plan layout of the water-resisting curtain disclosed by the present application;

[0024] Figure 2 It is a sectional view of the water-resisting curtain disclosed by the present application;

[0025] Figure 3 It is a structure diagram of the multi-hole detection guide pipe;

[0026] Figure 4 It is a butt joint schematic diagram of the pipe segments of the multi-hole detection guide pipe;

[0027] Figure 5 It is Figure 4 the enlarged view of A in FIG. 1;

[0028] Figure 6 It is a schematic diagram of the pressure bearing plate.

[0029] In the figure, the water-resisting curtain 1, the mixing pile 11, the Larsen steel sheet pile 12, the spiral flow well 2, the cylinder body 21, the bottom plate 22, the bottom sealing plate 24, the quicksand recharge area 25, the multi-hole detection guide pipe 3, the guide head 31, the pipe body 32, the pipe segment 321, the insertion step 322, the receiving step 323, the protective cap 33, the through hole 331, the detection meter 34, the fine-mesh permeable hole 35, the support end plate 36, the pressure bearing plate 37, the plate body 371, the insertion head 372. DETAILED DESCRIPTION

[0030] The present application will be further described below in combination with the drawings and examples as follows:

[0031] In this invention, the terms "above," "below," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the appendix. Figure 2 The orientations or positional relationships shown are for the purpose of describing the present invention only, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0032] The present invention discloses a method for caisson casting of vortex wells in high-water-level silty soil, comprising the following steps:

[0033] Step 1: Level the site, prepare for construction, measure and locate, and establish a control grid.

[0034] Before construction, the construction site must be leveled and a site plan prepared, including temporary power distribution, drainage, machinery and transportation access, material processing and storage areas, and construction work areas. Specific technical plans and safety briefings must be prepared, and the construction drawings and relevant technical specifications must be thoroughly reviewed. Based on the vortex well's positioning coordinates and cylinder diameter range in the construction drawings, the structural dimensions of the outer water-tight curtain 1 are determined. Measurement control points are established in the four cardinal directions (east, west, south, and north) around its perimeter, and perpendicular intersecting center positioning control axes are established. Using verified and designated primary control points, permanent and secure control points and axes are established on-site, marked and protected, and relevant parameters are recorded in detail.

[0035] Step 2: Construct the waterproof curtain 1. The waterproof curtain 1 is a combined waterproof curtain, including mixing piles 11 and Larssen steel sheet piles 12 arranged around the vortex well 2. The depth of the mixing piles 11 is greater than the design depth of the vortex well 2. Before the mixing piles 11 are completely bonded and cured, the Larssen steel sheet piles 12 are pressed into the formed mixing piles 11 one by one, so that the Larssen steel sheet piles 12 straddle the construction joint of the mixing piles 11.

[0036] Before the initial setting and hardening of the mixing pile 11, the porous probe 3 is pressed into the mixing pile 11. The porous probe 3 is located inside the Larssen steel sheet pile 12, and the probe 34 is inserted into the porous probe 3 for detection.

[0037] Among them, the mixing pile 11 is constructed using a deep mixing machine of appropriate specifications. The depth of the mixing pile 11 is usually about 0.5m deeper than the design depth of the vortex well, and the wall thickness is generally about 500-1200mm. Of course, these depth dimensions and wall thickness can be adjusted according to the site geological environment and structural dimensions. When it is narrower, a single-axis type can be used, and when it is wider, a multi-axis type can be used.

[0038] Before the complete cementation and solidification of the mixing pile 11, the static pressure pile machine or other pile driving machinery is used to press the Larsen steel sheet pile 12 into the formed mixing pile 11 one by one, so as to ensure that the Larsen steel sheet pile is tightly buckled, and the position can be in the middle of the mixing pile 11 along the radial direction of the mixing pile 11, or can be offset to the outside, but it is necessary to ensure that the Larsen steel sheet pile 12 can be completely wrapped by the mixing pile 11 to form a similar buried type water stop structure type, which effectively blocks the infiltration and recharge of underground water.

[0039] In order to speed up the construction progress, the mixing pile 11 and the Larsen steel sheet pile 12 can also be constructed synchronously, that is, after the completion of a section of the mixing pile 11, the static pressure pile construction of a section of the Larsen steel sheet pile 12 is started before the mixing pile 11 is completely solidified, without waiting for the completion of the construction of the whole mixing pile 11, so as to speed up the construction progress and reduce the necessary site safety maintenance and construction management.

[0040] In actual construction, in order to improve the water resistance effect of the water resistance curtain 1, an appropriate amount of anti-permeation additive can also be added during deep mixing to adjust the cement and fly ash mixing ratio to improve the density.

[0041] The combined water resistance curtain 1 of the “deep mixing pile + Larsen steel sheet pile” can be appropriately higher than the ground by a certain height during construction, so as to play a certain safety protection and blocking role, and avoid that the surrounding sundries fall into the well during the sinking process to cause object impact accidents.

[0042] Step 3, the cylinder 21 of the vortex well 2 is sunk.

[0043] After the completion of the combined water resistance curtain 1, the protective measures and monitoring measures before the sinking operation, the sinking operation is started. First, the necessary inspection and handover work is carried out, and after it is determined that the safety quality meets the requirements, the vortex well sinking operation special construction scheme is formulated according to the design depth and the cylinder wall structure size, and the sinking depth of each section of the vortex well is determined in detail. The sinking period plan and the process monitoring of the key technical parameters are formulated, which are recorded in detail, analyzed in time, corrected accurately and strictly controlled.

[0044] Step 4, the vortex well 2 bottom sealing 24 and bottom plate 22 construction; the multi-hole detection guide pipe 3 is filled.

[0045] After the sinking operation reaches the design depth and after a period of natural settlement and stabilization, the vortex well 2 bottom sealing 24 and bottom plate 22 structure construction is carried out according to the design requirements, and the cylinder structure construction is started. At this time, the multi-hole detection guide pipe 3 can no longer be used, and the self-compacting fine stone micro-expansion concrete with a higher grade than the cylinder wall structure is pumped and delivered into the multi-hole detection guide pipe 3, so that the concrete poured after the multi-hole detection guide pipe 3 can be tightly engaged with the formed mixing pile 11 after hardening, so as to ensure the overall strength and necessary density.

[0046] The Larsen steel sheet pile 12 is plate-shaped, and is pressed into the middle of the agitator pile 11 before the agitator pile 11 is hardened, and is integrated with the agitator pile 11 after the agitator pile 11 is hardened, to form a middle-buried water stop structure, and simultaneously forms a combined sheet pile structure, thereby improving the water stopping effect and the protection effect.

[0047] In the embodiment, the agitator pile 11 and the Larsen steel sheet pile 12 are combined to form a closed water-resisting curtain 1. A deep layer agitator is used to perform deep layer agitating and pouring and solidifying around the outer periphery of the spiral flow shaft wall, to form a deep layer agitator pile 11 with a certain width (usually about 500-100 mm). Before the deep layer agitator pile 11 is completely initial solidified, a static pile presser is used to press the Larsen steel sheet into the deep layer agitator pile 11 one by one. Of course, other pile driving machines can also be used, and the static pile presser is used only to reduce vibration and noise.

[0048] Compared with the traditional Larsen steel sheet pile and deep layer agitator pile separated structure, the agitator pile 11 and Larsen steel sheet pile 12 combined water-resisting curtain 1 disclosed in the application has the following advantages:

[0049] First, it is beneficial to shorten the construction period.

[0050] If the Larsen steel sheet pile 12 is constructed first, and then the deep layer agitator pile 11 is constructed inside the Larsen steel sheet pile 12, the construction period is relatively long, and the construction machinery is easy to damage the nearby Larsen steel sheet pile 12 which has been closed by joint construction. In order to speed up the construction progress, the deep layer agitator pile 11 and the Larsen steel sheet pile 12 can be constructed synchronously, to realize complete adhesion in construction organization, thereby greatly shortening the construction period.

[0051] Second, it is beneficial to control the construction quality.

[0052] Due to the soft and water-rich silt foundation, the separately arranged steel sheet pile is easy to slide and deviate, and it is difficult to control the positioning and joint connection quality, and it is difficult to ensure the formation of a good closed water-resisting curtain. In the application, the agitator pile 11 is formed by deep layer agitating, replacement and adjustment by using cement, fly ash and other solidifying cementitious materials. Before the agitator pile 11 is initial solidified, the Larsen steel sheet pile 12 is inserted into the agitator pile 11 and is integrated with the agitator pile 11. The homogeneous and dense mixture of the agitator pile 11 is combined with the Larsen steel sheet pile 12, which is more beneficial to the positioning construction of the Larsen steel sheet pile 12.

[0053] Third, the lateral stiffness and water-resisting performance are better.

[0054] The riding jointed Larsen steel sheet pile 12 has good waterproof effect, and the mixing pile 11 tightly wraps the Larsen steel sheet pile 11, forming a structure similar to a buried water-stop steel sheet, which not only has good anti-permeation and anti-corrosion effect, but also has tight engagement with the concave-convex pile surface of the Larsen steel sheet pile 12, so that the advantages of the Larsen steel sheet pile 12 and the mixing pile 11 can be fully utilized, and the lateral stiffness, stability and water resistance performance are more superior.

[0055] Fourthly, the combined water-resisting curtain has good guiding and protecting effects. Since the combined water-resisting curtain formed by accurate positioning and measurement control is provided with a cross control line, the center positioning control can also be performed by using the cross control line during the construction of the spiral flow well caisson; the perfect isolation of the surrounding soil of the water-resisting curtain not only reduces the influence on the surrounding site, but also plays a good protecting and guiding role for the operation of the spiral flow well caisson in the water-resisting curtain, so that the large inclination or deviation of the spiral flow well caisson in the water-rich and silt soil is avoided.

[0056] In summary, the combined water-resisting curtain formed by the mixing pile 11 and the Larsen steel sheet pile 12 has superior water-resisting effect, can cooperate with the pipe well rapid dewatering, and reduces the influence of the underground water on the caisson. The combined water-resisting curtain formed by the mixing pile 11 and the Larsen steel sheet pile 12 has good lateral stiffness, the positioning of the Larsen steel sheet pile 12 is reliable, the stiffness and stability of the water-resisting curtain are good, the lateral pressure of the surrounding soil can be better resisted, the safety and quality hidden dangers such as the sliding, inclination or deviation of the spiral flow well caisson are effectively relieved, and the quality and safety of the spiral flow well caisson are ensured.

[0057] In order to monitor the underground water condition and the water-resisting effect at any time, a plurality of multi-hole detection pipes 3 are arranged in the mixing pile 11 along the circumferential direction, as shown in Figure 3 The multi-hole detection pipe 3 is inserted into the mixing pile 11 in the vertical direction and is integrated with the mixing pile 11; and the multi-hole detection pipe 3 is located inside the Larsen steel sheet pile 12.

[0058] At least four multi-hole detection pipes 3 are arranged in the mixing pile 11, and the four multi-hole detection pipes 3 are respectively located in the southeast, southwest and northwest of the mixing pile 11, so as to monitor the underground water condition at any time and reflect the water-resisting effect. Of course, when the diameter of the spiral flow well is large, the multi-hole detection pipes 3 can be arranged more densely.

[0059] Preferably, the multi-hole detection pipe 3 comprises a pipe body 32 and a guide head 31 at the bottom end of the pipe body 32; the guide head 31 is a solid cone which gradually decreases from one end adjacent to the pipe body 32 to the bottom end in the axial direction; and a plurality of fine penetration holes 35 are distributed on the pipe body 32.

[0060] The guide head 31 of the solid cone reduces the resistance in the process of pile pressing drilling and improves the strength of the solid cone, so as to facilitate the fast drilling in the deep mixing pile 11 and to quickly reach the detection depth. The pipe body 32 is provided with a plurality of fine penetration holes 35 distributed thereon. On one hand, the fine penetration holes 35 facilitate the underground water to quickly penetrate into the pipe, so as to quickly understand the underground water level and provide parameters for the precipitation construction. On the other hand, after the completion, the slurry can quickly penetrate out of the fine penetration holes 35 when the slurry is injected into the multi-hole detection pipe 3 to plug the holes, so as to firmly connect the new and old concrete. The diameter of the fine penetration hole 35 is usually 3-5 mm.

[0061] In order to avoid the blockage caused by the falling of sundries into the pipe, preferably, the protective cap 33 is detachably connected to the top end of the pipe body 32. The top end of the pipe body 32 and the protective cap 33 can be connected by threads or the like. The protective cap 33 is provided with a through hole 331 through which the detection gauge 34 passes to detect. The actual detection is performed by using a folding rubber ruler or a telescopic water level detection gauge as the detection gauge 34, which penetrates through the through hole 331 and penetrates into the pipe to detect. In order to facilitate clear observation and identification, the detection gauge 34 can be made of a material which is easy to change color when soaked in water, such as color-changing ink.

[0062] After the completion of the deep mixing pile 11 and before the hardening of the deep mixing pile 11, the multi-hole detection pipe 3 can be slowly pressed into the deep mixing pile 11 by using a static pile press or other pile pressing method. The multi-hole detection pipe 3 is usually a pipe with a diameter of about 50-100 mm and a wall thickness of about 3-5 mm. Considering that the required multi-hole detection pipe 3 is relatively long, it may be inconvenient to operate during the pressing process on site. Preferably, as shown in Figure 4 and Figure 5 The pipe body 32 includes a plurality of pipe segments 321 along the axial direction. The bottom of the upper pipe segment 321 is inwardly retracted in the outer wall of the pipe segment 321 to form a plug-in step 322 between the two adjacent pipe segments 321. The top of the lower pipe segment 321 is outwardly expanded in the inner wall of the pipe segment 321 to form a receiving step 323. The upper pipe segment 321 is butted and connected with the lower pipe segment 321. Considering that the multi-hole detection pipe 3 may be blocked in the downward expansion gap when it continues to be pressed downward, which affects the sinking and joint deformation, the multi-hole detection pipe 3 is in the form of the upper pipe segment 321 being plugged into the lower pipe segment 321.

[0063] The multi-hole detection pipe 3 is divided into a plurality of pipe segments 321 which are connected by butting. In order to avoid the bending deformation of the pipe segment 321, a pressure plate 37 is detachably installed at the top end of the pipe segment 321 to uniformly bear the force and reduce the excessive deformation. After the corresponding pipe segment 321 is pressed in, the pressure plate 37 can be removed.

[0064] In order to facilitate the installation and removal of the pressure plate 37, as shown inFigure 6 As shown, the pressure plate 37 comprises a plate body 371 and a connector 372 arranged at the center of the bottom surface of the plate body 371, which is matched with the inner cavity of the pipe segment 321.

Claims

1. A method for caisson casting of vortex wells in silty soil with high water levels, characterized in that: Includes the following steps: Step 1: Site leveling, construction preparation, measurement and positioning, and establishment of control grid. Step 2: Construct a water-tight curtain (1). The water-tight curtain (1) is a combined water-tight curtain, including mixing piles (11) and Larssen sheet piles (12) arranged around the vortex well (2). The depth of the mixing piles (11) is greater than the design depth of the vortex well (2). Before the mixing piles (11) are completely bonded and cured, the Larssen sheet piles (12) are pressed into the formed mixing piles (11) one by one, so that the Larssen sheet piles (12) straddle the construction joint of the mixing piles (11) and are fixed together with the mixing piles (11). Before the initial setting and hardening of the mixing pile (11), the porous probe (3) is pressed into the mixing pile (11). The porous probe (3) is located inside the Larsen sheet pile (12). The probe (34) is inserted into the porous probe (3) for detection. Step 3: The cylinder (21) of the vortex well (2) is sunk. Step 4: Construction of bottom sealing (24) and bottom plate (22) of vortex well (2); sealing of multi-hole probe (3).

2. The method for caisson casting in high-water-level silty soil foundation as described in claim 1, characterized in that: The porous probe (3) includes a tube body (32) and a guide head (31) at the bottom end of the tube body (32); the guide head (31) is a solid cone that gradually narrows from one end adjacent to the tube body (32) to the bottom end along the axial direction; the tube body (32) has a plurality of fine permeation holes (35).

3. The method for caisson casting in high-water-level silty soil foundation as described in claim 2, characterized in that: A protective cap (33) is detachably connected to the top of the tube body (32), and a through hole (331) is provided on the protective cap (33) through which a capacitance detector (34) passes for detection.

4. The method for caisson casting in high-water-level silty soil as described in any one of claims 1-3, characterized in that: The multi-hole probe (3) is divided into several pipe segments (321) and pressed into the mixing pile (11) in the form of interlocking; when each pipe segment (321) is pressed in, a pressure plate (37) can be detachably installed at the top of the pipe segment (321); The pressure plate (37) includes a plate body (371) and a connector (372) disposed at the center of the bottom surface of the plate body (371), the connector (372) being adapted to the inner cavity of the pipe section (321).

5. The method for caisson casting in high-water-level silty soil as described in any one of claims 1-3, characterized in that: In step 4, self-compacting fine stone micro-expansion concrete with a grade higher than that of the vortex well (2) is poured into the porous probe (3). The self-compacting fine stone micro-expansion concrete seeps in from the fine permeation holes (35) dispersed on the wall of the porous probe (3) and tightly interlocks with the mixing pile (11).

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