Rigid-flexible coupling occlusion type deep foundation pit water stop supporting system and construction method thereof

Abstract

The invention discloses a rigid-flexible coupling occlusion type deep foundation pit water stop supporting system and a construction method thereof, relates to the technical field of deep foundation pit water stop supporting, solves the defects caused by the fact that existing occlusion piles adopt reinforced concrete piles and plain concrete piles for occlusion, and comprises main piles and auxiliary piles which are alternately arranged in an occlusion mode. The main pile is a reinforced concrete pile, and a vertical anchoring strip is arranged in the meshing area of the main pile and the adjacent auxiliary pile. The auxiliary piles are formed by pouring liquid solidified soil, and the liquid solidified soil of the auxiliary piles and the vertical anchoring strips on the main piles are wrapped, anchored and interlocked. The liquid solidified soil comprises the following components in percentage by weight: 18-22% of cement; 15%-20% of modified fly ash; 3%-5% of silica sol; 0.1%-0.3% of a composite retarder; 30%-35% of water; a field soil body: the balance; and the main pile is poured into the pile before the adjacent front auxiliary pile is initially set, the liquid solidified soil can be used for forming the pile in situ, soft cutting is achieved, the process interval is short, and the total construction period is short.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep foundation waterproof supporting, in particular to the improvement of the interlocking pile supporting structure. BACKGROUND

[0002] Generally, waterproof supporting is needed in the construction of foundation pits with a depth of more than 5 meters or complex geological conditions or special surrounding environment. Waterproof supporting includes waterproofing and supporting. Waterproofing is mainly to block the permeation path of underground water and reduce the inflow of water in the pit. Supporting is to resist the soil pressure and water pressure of the side wall of the foundation pit to prevent slope collapse and ensure construction safety and stability of the surrounding environment.

[0003] There are various ways of waterproof supporting, such as waterproof curtain, steel sheet pile supporting, interlocking pile, etc. The existing interlocking pile is generally formed by interlocking reinforced concrete main piles and plain concrete auxiliary piles to serve as supporting and waterproofing. The reinforced concrete main pile mainly serves as a force support, also known as a meat pile. The plain concrete auxiliary pile mainly serves as a seepage prevention, also known as a plain pile. The construction of the interlocking pile is generally carried out in the order of "jumping and hitting". The typical process is as follows: first, the odd-numbered auxiliary piles, i.e., the auxiliary piles with an interval of one pile, are constructed. Then, the adjacent main piles are constructed after the initial setting of the auxiliary pile concrete and before the final setting. When the main pile is constructed, the unhardened concrete of the adjacent auxiliary pile needs to be cut in the interlocking area. After the steel reinforcement cage is hoisted in the main pile hole and the concrete is poured, the main pile and the auxiliary pile are interlocked to achieve the purpose of waterproof supporting.

[0004] Since the existing interlocking pile adopts reinforced concrete piles and plain concrete piles for interlocking, it belongs to the interlocking of two rigid piles. On the material level, the construction interface is easy to diverge, and the risk of leakage is high. On the structural level, the bending stiffness is basically the same, and the anti-deformation ability is inconsistent, which is easy to produce deformation cracks. On the environmental protection level, the carbon emission of concrete is high, and the waste slag produced by drilling needs to be treated twice for harmless treatment. On the construction level, the interval time between the construction processes of the two pile bodies is long, and the construction period is long. SUMMARY

[0005] In view of the above, the present application aims to solve the above-mentioned problems of the existing interlocking pile which adopts reinforced concrete piles and plain concrete piles for interlocking, and proposes a rigid-flexible coupling interlocking deep foundation waterproof supporting system and a construction method thereof.

[0006] To solve the technical problems proposed in the present application, the technical scheme adopted is as follows: A rigid-flexible coupling occlusion type deep foundation water stop supporting system, comprising main piles and auxiliary piles arranged alternately in occlusion; characterized in that: the main piles are reinforced concrete piles, and vertical anchoring strips are arranged in the occlusion area of the main piles and the adjacent auxiliary piles; the auxiliary piles are formed by pouring liquid solidified soil, and the liquid solidified soil of the auxiliary piles and the vertical anchoring strips on the main piles are wrapped and interlocked; the weight percentage of the components of the liquid solidified soil is: Cement: 18%-22%; Modified fly ash: 15%-20%; Silica sol: 3%-5%; Composite retarder: 0.1%-0.3%; Water: 30%-35%; On-site soil: the balance; The main piles are poured into piles before the initial setting of the adjacent previous auxiliary piles.

[0007] The technical features further limiting the technical solution of the application include: The vertical anchoring strips protrude from the side surface of the main piles by a height of ≥50 mm and a width of ≥100 mm; and the occlusion width of the main piles and the auxiliary piles is 250-300 mm.

[0008] A reinforcing cage in the main pile is provided with a reinforcing bar inserted into the vertical anchoring strip.

[0009] The construction control method of the above-mentioned rigid-flexible coupling occlusion type deep foundation water stop supporting system comprises the following steps: a rotary drilling machine is used to first drill an auxiliary pile hole, then a steel casing with a convex groove is pressed into the side of the auxiliary pile hole to drill a main pile hole, after the main pile hole and the auxiliary pile hole are completed, a reinforcing cage is placed in the main pile hole, a grouting pipe is pre-buried in the reinforcing cage, and concrete is poured into the main pile hole through the grouting pipe by reverse construction at a grouting pressure greater than or equal to 2 MPa, after the main pile is poured into concrete and shaped, the liquid solidified soil is immediately poured into the auxiliary pile hole to form an auxiliary pile, and then the steel casing is pulled out; the pile edge of the auxiliary pile that has not yet been initially set is again subjected to the same main pile and auxiliary pile construction operation.

[0010] The liquid solidified soil poured into the auxiliary pile has a permeability coefficient ≤1×10⁻ 7 cm / s in the occlusion area with the surface of the main pile.

[0011] The liquid solidified soil poured into the auxiliary pile has an initial setting time ≥4 h and a 28-day compressive strength ≥10 MPa.

[0012] The beneficial effects of the present application are: the auxiliary pile of the present application is poured with liquid solidified soil, and is filled with the reinforced concrete main pile to form a micro-tooth-shaped lock structure; the reinforced concrete main pile provides anchoring type bending resistance bearing capacity, and the liquid solidified soil auxiliary pile only provides water stopping function, and the two are in good cooperation. The liquid solidified soil is obtained by on-site drilling of slag or waste mud + solidifying agent (mainly slag-based cementitious material), and the liquid solidified soil can be formed into a pile in situ, soft cutting, short process interval, and short total construction period; and is suitable for deep foundation pit engineering under complex geological conditions such as high water level sand layer and coastal soft soil. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a top view structural schematic diagram of the rigid-flexible coupling occlusion type deep foundation pit water stopping support system of the present application. Figure 2 It is a main pile cross-sectional structural schematic diagram of the present application. DETAILED DESCRIPTION

[0014] The technical solutions of the present application are further described below in combination with the preferred specific embodiments of the present application.

[0015] Referring to Figure 1 and Figure 2 , the present application discloses a rigid-flexible coupling occlusion type deep foundation pit water stopping support system, which comprises main piles 1 and auxiliary piles 2 arranged alternately in occlusion; the diameters of the main piles 1 and the auxiliary piles 2 are both 1000mm, the center-to-center distance between the two main piles 1 and the center-to-center distance between the two auxiliary piles are both 1600mm, and the depth of the main pile is greater than that of the auxiliary pile. The main pile 1 is a reinforced concrete pile, the depth of which is greater than that of the auxiliary pile, and mainly plays a role of force bearing support; in order to ensure the occlusion reliability between the main pile 1 and the adjacent auxiliary pile 2, a vertical anchoring strip 11 is arranged in the occlusion area between the main pile 1 and the adjacent auxiliary pile 2; the auxiliary pile 2 is formed by pouring liquid solidified soil, and the liquid solidified soil of the auxiliary pile 2 is wrapped and anchored with the vertical anchoring strip 11 on the main pile 1; compared with the traditional plain concrete auxiliary pile, the auxiliary pile 2 of the present application has a certain flexibility, the liquid solidified soil can also wrap the vertical anchoring strip 11 on the main pile 1, and micro-locked with the surface of the main pile 1, and the relative two rigid piles are occluded, the construction interface of the present application is not easy to diverge, the leakage risk is low, and deformation cracks are not easy to occur.

[0016] The weight percentage of the liquid solidified soil composition is: Cement: 18%~22%; the cement is P.O 42.5 ordinary portland cement; Modified fly ash: 15%~20%; the modified fly ash is obtained by activating the fly ash with nano CaO (calcium oxide); Silica sol: 3%~5%; the role of the silica sol is to enhance the permeability; Composite retarder: 0.1%~0.3%; the role of the composite retarder is to control the initial setting time ≥4h; Water: 30%~35%; On-site soil: remaining quantity; To achieve the interlocking and anchoring of the liquid-solidified soil of the auxiliary pile 2 with the vertical anchoring strip 11 on the main pile 1, the main pile 1 must be cast before the adjacent auxiliary pile 2 has initially set. In the construction industry, when cement particles come into contact with water, the main components such as tricalcium silicate and dicalcium silicate react chemically with the water to generate hydrated calcium silicate (CSH gel), calcium hydroxide, and other hydration products. As the reaction proceeds, the hydration products gradually increase and interconnect, forming a preliminary spatial network structure. This causes the material to gradually lose its fluidity and plasticity from its initial fluid state (can be poured, vibrated, smoothed, etc.). The starting point of this transformation is the initial setting. GB 175 (General Portland Cement) stipulates that the initial setting of cement paste should be tested using a Vicat apparatus: a standard needle (1.13 mm in diameter) is vertically inserted into the paste. When the needle sinks to a depth of 4 mm ± 1 mm (i.e., the tip of the needle is about 4 mm from the bottom of the container), it is considered to be in the initial setting state.

[0017] In this invention, the dimensions of the vertical anchoring strip 11 are preferably: the height protruding from the side surface of the main pile 1 is ≥50mm, and the width is ≥100mm; the width at the interlocking point between the main pile 1 and the auxiliary pile is 250~300mm.

[0018] To ensure the strength of the vertical anchoring strip, such as Figure 2 As shown, the main pile 1 has reinforcing bars 12 inserted into the vertical anchor bars on the steel cage.

[0019] The construction control method for implementing the above-mentioned rigid-flexible coupled interlocking deep foundation pit water-stopping support system disclosed in this invention involves first drilling auxiliary pile holes using a rotary drilling rig, then pressing a steel casing with a groove into the side of the auxiliary pile hole to drill the main pile hole. After completing the main pile hole and auxiliary pile hole, a reinforcing cage is placed in the main pile hole, and a grouting pipe is pre-embedded in the reinforcing cage. Concrete is poured into the main pile hole through the grouting pipe at a grouting pressure greater than or equal to 2MPa. After the main pile concrete is formed, liquid solidified soil is immediately poured into the auxiliary pile hole to form the auxiliary pile, and then the steel casing is pulled out. The same main pile and auxiliary pile construction operations are repeated at the pile edge of the auxiliary pile before initial setting.

[0020] The self-leveling properties of the liquid-solidified soil used for casting the auxiliary piles in this invention are as follows: slump ≥ 260 mm, capable of self-filling 0.2 mm cracks. Strength gain: 3-day strength ≥ 3 MPa, 28-day strength ≥ 10 MPa (more than twice that of traditional cement-soil). The permeability coefficient of the liquid-solidified soil used for casting the auxiliary piles in the interlocking area with the main pile surface is ≤ 1 × 10⁻ 7 cm / s. The initial setting time of the liquid-solidified soil for the secondary piles is ≥4h, and the 28-day compressive strength is ≥10MPa.

[0021] The double composite clamping mechanism is realized: Macroscopic clamping: the reinforced concrete main pile 1 and the liquid solidified soil auxiliary pile 2 are arranged in plane alternation, and the clamping width is 250-300 mm.

[0022] Microscopic interlocking: the liquid solidified soil (viscosity <= 50 Pa s) penetrates into the main pile surface convex groove (depth 50 mm, width 100 mm), and forms a lock type anchoring.

[0023] The bending bearing capacity (kN m) of the application is 1200, the permeability coefficient (cm / s) is 1x10 6 | 1x10 7 | reduced by 10 times | carbon emission (kgCO2 / m³) | 380 (concrete) | 220 (solidified soil) | -42% |.

[0024] Solidification monitoring and parameter adjustment synchronization: based on the BIM model, the grouting pressure and flow are fed back in real time, and the proportioning is dynamically optimized.

[0025] Stress monitoring and structure checking synchronization: the optical fiber grating sensor monitors the pile deformation, and automatically checks the design safety factor.

[0026] Compared with the traditional construction process, the water sealing performance of the application is realized through microscopic interlocking + chemical plugging; the main pile and the auxiliary pile are almost synchronous reverse operation, which can save 30% construction period, and the construction efficiency is greatly improved; the on-site soil is reused during the pouring of the auxiliary pile, the material cost is reduced by 25% through solid waste utilization, and the whole process can be digitized by using BIM + sensor.

Claims

1. A rigid-flexible coupled interlocking deep foundation pit water-stopping support system, comprising alternating interlocking main piles and auxiliary piles; characterized in that: The main pile is a reinforced concrete pile, and vertical anchoring strips are provided in the interlocking area between the main pile and the adjacent secondary pile; the secondary piles are formed by pouring liquid-solidified soil, and the liquid-solidified soil of the secondary piles is interlocked with the vertical anchoring strips on the main piles; the weight percentage of the liquid-solidified soil is as follows: Cement: 18%~22%; Modified fly ash: 15%~20%; Silica sol: 3%~5%; Composite retarder: 0.1%~0.3%; Water: 30%~35%; On-site soil: remaining quantity; The main pile is cast into a pile before the adjacent preceding pile has initially set.

2. The rigid-flexible coupling interlocking deep foundation pit water-stopping support system according to claim 1, characterized in that: The vertical anchoring strip protrudes from the side surface of the main pile by a height ≥ 50mm and a width ≥ 100mm; the width at the interlocking point between the main pile and the auxiliary pile is 250~300mm.

3. The rigid-flexible coupling interlocking deep foundation pit water-stopping support system according to claim 1, characterized in that: The main pile has reinforcing cages with insert bars that are inserted into vertical anchor bars.

4. The construction control method for a rigid-flexible coupled interlocking deep foundation pit water-stopping support system as described in claim 1, characterized in that: First, a secondary pile hole is drilled using a rotary drilling rig. Then, a steel casing with a groove is pressed into the side of the secondary pile hole to start drilling the main pile hole. After the main pile hole and secondary pile hole are completed, a reinforcing cage is placed in the main pile hole. A grouting pipe is pre-embedded in the reinforcing cage. Concrete is poured into the main pile hole through the grouting pipe at a grouting pressure greater than or equal to 2MPa. After the main pile concrete is formed, liquid solidified soil is poured into the secondary pile hole to form the secondary pile. Then, the steel casing is pulled out. The same main pile and secondary pile construction operation is repeated at the pile edge of the secondary pile before it has initially set.

5. The construction control method for a rigid-flexible coupled interlocking deep foundation pit water-stopping support system according to claim 4, characterized in that: The permeability coefficient of the liquid-solidified soil poured for the secondary piles in the interlocking area with the surface of the main piles is ≤1×10⁻ 7 cm / s.

6. The construction control method for a rigid-flexible coupled interlocking deep foundation pit water-stopping support system according to claim 4, characterized in that: The initial setting time of the liquid solidified soil for the secondary piles is ≥4h, and the compressive strength after 28 days is ≥10MPa.

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