Composite supporting structure for deep foundation pit
By using a composite support structure of steel sheet piles, cement mixing piles and bored piles in deep foundation pits, the problem of insufficient rigidity of the deep foundation pit support structure in silt soft soil layers was solved, the effects of anti-slip, anti-collapse and water-stopping were achieved, and the safety and stability of the silt soft soil layers were improved.
Patent Information
- Application Number
- CN202422720212.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-10-14
- Estimated Expiration
- 2034-11-08
AI Technical Summary
In the silt soft soil environment, the supporting structure of the deep foundation pit has low stiffness, the anti-uplift safety factor of the silt soft soil layer at the bottom of the foundation pit is low, and the water-stopping performance of the silt soft soil layer is poor, resulting in the risk of slippage, collapse and water gushing during foundation pit construction.
A composite support structure consisting of steel sheet pile retaining walls, cement mixing pile retaining walls and bored piles is adopted, including a bottom concrete layer and steel pipe internal supports, to form a steel tube concrete support structure to enhance the support stiffness; a rectangular waterproof structure is formed by the cement mixing pile retaining walls and the bottom concrete layer to prevent groundwater infiltration; a rectangular frame-type rigid anti-floating structure is formed to increase the weight of the bottom sealing components at the bottom of the foundation pit.
It effectively enhances the rigidity of the deep foundation pit support structure, prevents side wall slippage and collapse, improves the water-stopping performance of the silt soft soil layer, prevents groundwater infiltration and leakage of construction wastewater, and enhances the anti-uplift safety of the silt soft soil at the bottom of the foundation pit.
Smart Images
Figure CN223433833U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to bridge bearing platform foundation pit engineering construction technical field, especially, relate to a kind of deep foundation pit composite support structure. BACKGROUND
[0002] In underground structure foundation pit engineering construction, to ensure the safety of underground structure construction and the environment around foundation pit, foundation pit support is the support, reinforcement and protection measures used to foundation pit side wall and surrounding environment, to ensure that foundation pit excavation and main structure construction can be smoothly implemented. Common foundation pit support has: pile support, pile brace, pile anchor, pile cantilever, underground diaphragm wall support, diaphragm wall+support, cement retaining wall, soil nailing wall (spray anchor support), reverse arch wall, undisturbed soil slope, pile, wall and support system, simple horizontal support, reinforced concrete pile etc.
[0003] In a bridge engineering in Guangdong delta plain, bridge 7# main pier bearing platform penetrates silty clay layer, medium sand layer, silt silty sand layer, silt silty clay layer, and is located on silt silty clay layer. The natural moisture content of soil layer in the construction site of the bridge 7# main pier bearing platform is 28.7-49.5%, water saturation is 88.3-99.0%, void ratio is 0.790-1.319, foundation bearing capacity is 50-220kPa, direct quick shear cohesion is 3.8-14.8kPa, internal friction angle is 2.3°-13.7°, the moisture content is high, the void ratio is large, the bearing capacity is low, the shear strength is low, the physical and mechanical properties of soil body are poor, the geological condition is poor, the lateral support force of bridge 7# main pier bearing platform foundation pit cofferdam is small, and it is easy to produce slip, collapse instability, so the unconventional foundation pit support is needed.
[0004] Based on the position of the bridge 7# main pier bearing platform near the nearest distance of about 3m of secondary water source Meixi River, the bearing platform foundation pit is water excavation 7.5m deep foundation pit, in order to prevent the bearing platform foundation pit from producing slip, collapse instability, and the silt soft soil layer from appearing uplift, water gushing accident after excavation due to low strength of silt soft soil layer and small lateral support force.
[0005] Therefore, in the construction of 7# main pier bearing platform foundation pit, how to develop deep foundation pit support structure with large rigidity, high anti-uplift safety factor of silt soft soil layer at the bottom of foundation pit and good water stopping performance of silt soft soil layer in silt soft soil layer environment is the problem to be solved urgently in the safe construction of the bridge 7# main pier bearing platform foundation pit. UTILITY MODEL CONTENTS
[0006] The utility model provides a kind of deep foundation pit composite support structure to solve the technical problems of deep foundation pit support structure with small rigidity, low anti-uplift safety factor of silt soft soil layer at the bottom of foundation pit and poor water stopping performance of silt soft soil layer in silt soft soil layer environment.
[0007] The technical scheme adopted by the utility model is as follows:
[0008] A deep foundation pit composite support structure, comprising: a steel sheet pile retaining wall for forming a temporary circumferential wall surface of a deep foundation pit, an outer pit cement mixing pile retaining wall for reinforcing a silt soft soil layer outside the deep foundation pit, an inner pit cement mixing pile retaining wall for reinforcing a silt soft soil layer below the deep foundation pit, and a plurality of cast-in-place piles, a bottom sealing concrete layer for forming a deep foundation pit bottom plate, and a steel pipe inner support for supporting within the deep foundation pit; the steel sheet pile retaining wall extends along the circumference of the deep foundation pit and vertically extends into the silt soft soil layer below the deep foundation pit; the plurality of cast-in-place piles are dispersed and vertically downwardly extend into the silt soft soil layer below the deep foundation pit, the outer pit cement mixing pile retaining wall is arranged in the silt soft soil layer outside the deep foundation pit and closely abuts the outer side wall of the steel sheet pile retaining wall, the inner pit cement mixing pile retaining wall is arranged in the silt soft soil layer below the deep foundation pit and closely abuts the inner side wall of the steel sheet pile retaining wall, and the cast-in-place piles are arranged to avoid the inner pit cement mixing pile retaining wall, and the bottom sealing concrete layer is arranged at the top end of the inner pit cement mixing pile retaining wall; the steel pipe inner support is tightly arranged between the steel sheet pile retaining walls on opposite sides and between the steel sheet pile retaining walls on adjacent sides.
[0009] Further, the bottom elevation of the inner pit cement mixing pile retaining wall is higher than the bottom elevation of the steel sheet pile retaining wall, and the bottom elevation of the steel sheet pile retaining wall is higher than the bottom elevation of the cast-in-place piles.
[0010] Further, the plurality of cast-in-place piles are uniformly and spacedly arranged at the two ends in the length direction of the deep foundation pit, and the pile top of each cast-in-place pile extends out after being upwardly arranged through the inner pit cement mixing pile retaining wall and the bottom sealing concrete layer, so as to extend into the pile cap poured in the deep foundation pit in the later stage. The top elevation of the plurality of cast-in-place piles is higher than the top elevation of the inner pit cement mixing pile retaining wall, and the top elevation of the plurality of cast-in-place piles is higher than the top elevation of the bottom sealing concrete layer; the bottom elevation of the bottom sealing concrete layer is higher than the bottom elevation of the outer pit cement mixing pile retaining wall, and the bottom elevation of the bottom sealing concrete layer is the same as the top elevation of the inner pit cement mixing pile retaining wall.
[0011] Further, the inner pit cement mixing pile retaining wall comprises a hollow frame type rectangular cement mixing pile retaining wall and a multi-surface straight line type straight support cement mixing pile retaining wall; the multi-surface straight line type straight support cement mixing pile retaining walls are sequentially and spacedly arranged along the length direction of the rectangular cement mixing pile retaining wall, and the two sides in the width direction of each straight support cement mixing pile retaining wall are connected with the rectangular cement mixing pile retaining wall.
[0012] Furthermore, the quasi-rectangular cement mixing pile retaining wall includes an inner rectangular cement mixing pile retaining wall and an outer rectangular cement mixing pile retaining wall that are fitted together and spaced apart, and a special-shaped cement mixing pile retaining wall connected therebetween; the outer rectangular cement mixing pile retaining wall is extended along the circumference of the deep foundation pit and is close to the inner side wall of the steel sheet pile retaining wall; the straight support cement mixing pile retaining wall is respectively connected to the inner rectangular cement mixing pile retaining wall, the outer rectangular cement mixing pile retaining wall and the special-shaped cement mixing pile retaining wall at both ends along the width direction.
[0013] Furthermore, the special-shaped cement mixing pile retaining wall includes an H-shaped cement mixing pile retaining wall connected at both ends of the deep foundation pit in the length direction and located between two adjacent cast-in-place piles in the outermost layer, a quasi-full-area cement mixing pile retaining wall connected at each top corner between the outer rectangular cement mixing pile retaining wall and the inner rectangular cement mixing pile retaining wall, and a one-shaped cement mixing pile retaining wall connected between two adjacent straight-supported cement mixing pile retaining walls.
[0014] Furthermore, the number of steel pipe internal supports is two layers, and the two layers of steel pipe internal supports are spaced parallel to each other in the upper and lower directions, and each layer of steel pipe internal supports includes multiple straight steel pipe internal supports and multiple inclined steel pipe internal supports; multiple inclined steel pipe internal supports are arranged at both ends of the deep foundation pit, and the two ends of each inclined steel pipe internal support are respectively connected to the inner walls of the two adjacent steel sheet pile retaining walls; multiple straight steel pipe internal supports are arranged between the inclined steel pipe internal supports arranged at both ends of the deep foundation pit in the length direction, and are arranged in sequence along the length direction of the deep foundation pit, and the two ends of each straight steel pipe internal support are respectively connected to the inner walls of the two opposite steel sheet pile retaining walls in the length direction of the deep foundation pit.
[0015] Furthermore, the straight steel tube internal support and the inclined steel tube internal support have the same structural settings. The straight steel tube internal support includes: two steel purlins fixed on the inner walls of the two opposite steel sheet pile retaining walls in the length direction of the deep foundation pit, a steel corbel connected between each steel purlin and the inner wall of the corresponding steel sheet pile retaining wall, and a steel tube support rod connected between the two steel purlins.
[0016] Furthermore, the deep foundation pit composite support structure also includes an outside-pit cement mixing pile retaining wall for reinforcing the silt soft soil layer outside the deep foundation pit. The outside-pit cement mixing pile retaining wall is arranged along the circumference of the deep foundation pit and is close to the outer wall of the steel sheet pile retaining wall.
[0017] Furthermore, the top elevation of the cement mixing pile retaining wall outside the pit is lower than the top elevation of the steel sheet pile retaining wall, and the bottom elevation of the cement mixing pile retaining wall outside the pit is lower than the top elevation of the cement mixing pile retaining wall inside the pit, so that the cement mixing pile retaining wall outside the pit and the cement mixing pile retaining wall inside the pit partially overlap in the vertical direction.
[0018] The utility model has the following beneficial effects:
[0019] The deep foundation pit composite support structure of the utility model, through the bottom sealing concrete layer arranged in the pit, the pit cement mixing pile enclosure wall, the pit cement mixing pile enclosure wall outside the pit, the steel sheet pile enclosure wall and the steel pipe inner support, a steel pipe concrete support structure is formed, compared with the traditional foundation pit support mode, the utility model support structure can effectively enhance the deep foundation pit support structure rigidity, resist the soil body sliding, collapse instability of the sidewall around the pit, in the utility model structure, through the pit cement mixing pile enclosure wall, the bottom sealing concrete layer, the steel sheet pile enclosure wall and the pit cement mixing pile enclosure wall outside the pit, a rectangular "water cup" type waterproof structure is formed, compared with the traditional foundation pit support mode, the utility model can effectively prevent the underground water from seeping into the pit or the construction sewage in the pit from seeping out of the pit to pollute the river water, thereby improving the water stopping performance of the silt soft soil layer, in the utility model structure, through the pit cement mixing pile enclosure wall and the bottom sealing concrete layer, a rectangular "frame" type rigid anti-floating structure is formed, compared with the traditional foundation pit support mode, the utility model can effectively increase the weight of the bottom sealing component of the pit, resist the silt soft soil body layer of the pit bottom from appearing uplift and water gushing accidents, thereby improving the uplift safety factor of the silt soft soil body of the pit bottom.
[0020] In addition to the purposes, features and advantages described above, the utility model has other purposes, features and advantages. The utility model will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS
[0021] The drawings that form a part of this application are intended to provide further understanding of the utility model, and the schematic embodiments of the utility model and the description thereof are used to explain the utility model, and do not constitute improper limitation on the utility model. In the drawings:
[0022] Figure 1 It is the deep foundation pit composite support structure layout plane schematic view of the utility model preferred embodiment;
[0023] Figure 2 It is the deep foundation pit composite support structure layout elevation schematic view of the utility model preferred embodiment;
[0024] Figure 3 It is the steel sheet pile and the connection structure diagram;
[0025] Figure 4 It is the silt soft soil layer reinforcement plane layout schematic view;
[0026] Figure 5 It is Figure 4 The 1-1 direction in the structure schematic view;
[0027] Figure 6 It is Figure 4 The 2-2 direction in the structure schematic view.
[0028] Legend:
[0029] 1, silt soft soil layer; 2, cast-in-place pile;
[0030] 3, cement mixing pile retaining wall; 301, cement mixing pile retaining wall outside the pit;
[0031] 302, cement mixing pile retaining wall inside the pit; 3021, rectangular-like cement mixing pile retaining wall; 30211, outer layer rectangular cement mixing pile retaining wall; 30212, inner layer rectangular cement mixing pile retaining wall; 30213, special-shaped cement mixing pile retaining wall; 302131, H-shaped cement mixing pile retaining wall; 302132, full-area-like cement mixing pile retaining wall; 302133, linear cement mixing pile retaining wall;
[0032] 3022, straight support cement mixing pile retaining wall;
[0033] 4, steel sheet pile retaining wall;
[0034] 5, steel pipe inner support; 501, straight steel pipe inner support; 5011, steel corbel; 5012, steel encasing purlin; 5013, steel pipe support rod; 502, inclined steel pipe inner support;
[0035] 6, bottom sealing concrete layer. DETAILED DESCRIPTION
[0036] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered below.
[0037] Reference Figures 1-2 and Figure 4 The preferred embodiment of the present application provides a deep foundation pit composite support structure, comprising: a steel sheet pile retaining wall 4 for forming a temporary circumferential wall surface of a deep foundation pit, a cement mixing pile retaining wall outside the pit 301 for reinforcing a silt soft soil layer 1 outside the deep foundation pit, a cement mixing pile retaining wall inside the pit 302 for reinforcing the silt soft soil layer 1 below the deep foundation pit, and a plurality of cast-in-place piles 2, a bottom sealing concrete layer 6 for forming a bottom plate of the deep foundation pit, and a steel pipe inner support 5 for supporting inside the deep foundation pit. The steel sheet pile retaining wall 4 extends along the circumference of the deep foundation pit and vertically extends into the silt soft soil layer 1 below the deep foundation pit. The plurality of cast-in-place piles 2 are dispersed and vertically downwardly extend into the silt soft soil layer 1 below the deep foundation pit. The cement mixing pile retaining wall outside the pit 301 is arranged in the silt soft soil layer 1 outside the deep foundation pit and closely adheres to the outer side wall of the steel sheet pile retaining wall 4. The cement mixing pile retaining wall inside the pit 302 is arranged in the silt soft soil layer 1 below the deep foundation pit and closely adheres to the inner side wall of the steel sheet pile retaining wall 4, and avoids the cast-in-place piles 2. The bottom sealing concrete layer 6 is arranged at the top end of the cement mixing pile retaining wall inside the pit 302. The steel pipe inner support 5 is tightly supported between the two opposite steel sheet pile retaining walls 4 and between the two adjacent steel sheet pile retaining walls 4.
[0038] In the deep foundation pit composite support structure of the present invention, a steel tube concrete support structure is formed by a bottom concrete layer 6 arranged at the bottom of the foundation pit, a cement mixing pile enclosure wall 302 in the pit, a cement mixing pile enclosure wall 301 outside the pit, a steel sheet pile enclosure wall 4 and a steel pipe inner support 5. Compared with the traditional foundation pit support method, the present invention can effectively enhance the rigidity of the deep foundation pit support structure and resist the sliding and collapse of the soil on the side walls around the foundation pit. In the present invention, the cement mixing pile enclosure wall 302 in the pit, the bottom concrete layer 6, the steel sheet pile enclosure wall 4 and the cement mixing pile enclosure wall 301 outside the pit are provided. 1 forms a rectangular "water cup" type waterproof structure. Compared with the traditional foundation pit support method, it can effectively prevent groundwater from seeping into the foundation pit or construction sewage in the foundation pit from seeping into the nearby river outside the foundation pit and polluting the river water quality, thereby improving the water-stopping performance of the silt soft soil layer 1; in this new structure, a rectangular "frame" type rigid anti-floating structure is formed by the cement mixing pile retaining wall 302 in the pit and the bottom sealing concrete layer 6. Compared with the traditional foundation pit support method, it can effectively increase the weight of the bottom sealing component of the foundation pit bottom, prevent the silt soft soil layer 1 at the bottom of the foundation pit from heaving and water gushing, thereby improving the anti-heaving safety factor of the silt soft soil body at the bottom of the foundation pit.
[0039] Alternatively, as Figure 2 As shown, the bottom elevation of the cement mixing pile retaining wall 302 in the pit is higher than the bottom elevation of the steel sheet pile retaining wall 4, and the bottom elevation of the steel sheet pile retaining wall 4 is higher than the bottom elevation of the cast-in-place pile 2. In the actual design, 30 cast-in-place piles 2 with a length of 128m, a diameter of 2.2m, and C35 concrete were constructed. The steel sheet pile retaining wall 4 uses PU600×210×18mm steel sheet piles made of Q355P and 18m long; combined with Figure 3 As shown, the steel sheet pile consists of a web, a wing plate and a lock, wherein: one end of the wing plate is welded to the lock, and the other end is welded to any end of the web to form a "U" shape, the lock end is set away from the web, and the steel sheet pile opening is opposite to the lock opening; the reverse "U-shaped protrusion" design of the locks on both outer sides of each steel sheet pile can be used to chain adjacent steel sheet piles to form an interlocking structure, and a watertight structure is formed when the steel sheet piles are interlocked, thereby increasing the strength of the steel sheet pile retaining wall 4 structure. After the cavity between the base and the steel sheet pile retaining wall 4 is backfilled with soil, the steel sheet pile needs to be removed.
[0040] Preferably, if Figure 2As shown, multiple cast-in-place piles 2 are evenly spaced at both ends of the deep foundation pit in the longitudinal direction, and the top of each cast-in-place pile 2 extends upward through the cement mixing pile retaining wall 302 and the bottom concrete layer 6 in the pit, so as to be extended into the pedestal cast in the deep foundation pit at a later stage; the top elevation of multiple cast-in-place piles 2 is higher than the top elevation of the cement mixing pile retaining wall 302 in the pit, and the top elevation of multiple cast-in-place piles 2 is higher than the top elevation of the bottom concrete layer 6; the bottom elevation of the bottom concrete layer 6 is higher than the bottom elevation of the cement mixing pile retaining wall 301 outside the pit, and the bottom elevation of the bottom concrete layer 6 is the same as the top elevation of the cement mixing pile retaining wall 302 in the pit, so as to further enhance the reinforcement effect of the silt soft soil layer 1 and the rigidity of the steel tube concrete support structure. Figure 2 As shown, the bottom sealing concrete layer 6 in the foundation pit and the cement mixing pile retaining wall 302 in the pit form a rectangular "frame" type rigid anti-floating structure, which increases the weight of the bottom sealing component of the foundation pit and prevents the silt soft soil layer 1 at the bottom of the foundation pit from uplifting and water gushing, thereby improving the anti-uplift safety factor of the silt soft soil at the bottom of the foundation pit; the bottom sealing concrete layer 6, together with the cement mixing pile retaining wall 302 in the pit, the cement mixing pile retaining wall 301 outside the pit, the steel sheet pile retaining wall 4 and the steel pipe inner support 5, forms a steel tube concrete support structure, which enhances the rigidity of the deep foundation pit support structure and resists the sliding and collapse of the soil on the side walls around the foundation pit; the bottom sealing concrete layer 6, together with the cement mixing pile retaining wall 302 in the pit, the steel sheet pile retaining wall 4 and the cement mixing pile retaining wall 301 outside the pit, forms a rectangular "water cup" type waterproof structure, which prevents groundwater from seeping into the foundation pit or construction sewage in the foundation pit from seeping into the nearby river outside the foundation pit and polluting the river water quality, thereby improving the water-stopping performance of the silt soft soil layer 1.
[0041] Alternatively, as Figure 4 As shown, the pit cement mixing pile retaining wall 302 includes a hollow frame-type, quasi-rectangular cement mixing pile retaining wall 3021 and a multi-faceted, linear, straight-support cement mixing pile retaining wall 3022. The multi-faceted, linear, straight-support cement mixing pile retaining walls 3022 are arranged in sequence along the length of the quasi-rectangular cement mixing pile retaining wall 3021, and each straight-support cement mixing pile retaining wall 3022 is connected to the quasi-rectangular cement mixing pile retaining wall 3021 on both sides of the width direction.
[0042] In this option, if Figures 4-6As shown, the quasi-rectangular cement mixing pile retaining wall 3021 comprises an inner layer of quasi-rectangular cement mixing pile retaining wall 30212 and an outer layer of quasi-rectangular cement mixing pile retaining wall 30211 which are nested and spaced apart, and a special-shaped cement mixing pile retaining wall 30213 connected between the two. The outer layer of quasi-rectangular cement mixing pile retaining wall 30211 is arranged along the circumference of the deep foundation pit and closely adheres to the inner side wall of the steel sheet pile retaining wall 4. The straight support cement mixing pile retaining wall 3022 is connected to the inner layer of quasi-rectangular cement mixing pile retaining wall 30212 and the outer layer of quasi-rectangular cement mixing pile retaining wall 30211 and the special-shaped cement mixing pile retaining wall 30213 at both ends in the width direction, respectively. In actual construction, on the top surface of the silt soft soil layer 1 inside the steel sheet pile retaining wall 4 on the four sides of the foundation pit, a plurality of cement mixing piles with a length of 6.0 m are constructed in three rows (width 1.5 m) towards the center side of the foundation pit, the plurality of cement mixing piles are connected to each other in the longitudinal and transverse directions to form the outer layer of quasi-rectangular cement mixing pile retaining wall 30211, and the outer layer of quasi-rectangular cement mixing pile retaining wall 30211 abuts against the inner side wall of the steel sheet pile retaining wall 4. After construction is completed, the outer layer of quasi-rectangular cement mixing pile retaining wall 30211 is firmly bonded with the steel sheet pile retaining wall 4. Similarly, in actual construction, on the top surface of the silt soft soil layer 1 at a position 3.75 m away from the inner edge of the outer layer of quasi-rectangular cement mixing pile retaining wall 30211 towards the center side of the foundation pit, a plurality of cement mixing piles with a length of 6.0 m are constructed in two rows (width 1.05 m) towards the center side of the foundation pit, and the plurality of cement mixing piles are connected to each other in the longitudinal and transverse directions to form the inner layer of quasi-rectangular cement mixing pile retaining wall 30212. In actual construction, on the top surface of the silt soft soil layer 1 inside the steel sheet pile retaining wall 4 at the middle position of the length side of the foundation pit, a plurality of cement mixing piles with a length of 6.0 m are constructed in five rows which are parallel to each other and have a width of 1.5 m (three rows), a transverse adjacent spacing of 2.5 m, and the plurality of cement mixing piles are connected to each other in the longitudinal and transverse directions to form the straight support cement mixing pile retaining wall 3022 which abuts against the outer layer of quasi-rectangular cement mixing pile retaining wall 30211, the special-shaped cement mixing pile retaining wall 302133 and the inner layer of quasi-rectangular cement mixing pile retaining wall 30212 at both ends, respectively.
[0043] Further, as shown in Figures 4-6 the special-shaped cement mixing pile retaining wall 30213 comprises an H-shaped cement mixing pile retaining wall 302131 connected between the two adjacent cast-in-place piles 2 at the two ends of the length direction of the deep foundation pit and located at the outermost layer, a quasi-full-area cement mixing pile retaining wall 302132 connected at each corner between the outer layer of quasi-rectangular cement mixing pile retaining wall 30211 and the inner layer of quasi-rectangular cement mixing pile retaining wall 30212, and a special-shaped cement mixing pile retaining wall 302133 connected between the two adjacent straight support cement mixing pile retaining walls 3022.
[0044] In actual construction, on the top surface of the silt soft soil layer 1 between the three adjacent cast-in-place piles 2 of the left half of the foundation pit in the bridge direction, a plurality of H-shaped cement mixing piles 302131 in the shape of "H" with double rows (width 1.05 m) and pile length 6.0 m are respectively constructed, the two ends of which respectively abut the outer layer rectangular cement mixing pile retaining wall 30211 and the inner layer rectangular cement mixing pile retaining wall 30212, and part of which respectively abut the adjacent cast-in-place piles 2. Similarly, on the top surface of the silt soft soil layer 1 between the three adjacent cast-in-place piles 2 of the right half of the foundation pit in the bridge direction, a plurality of H-shaped cement mixing pile retaining walls 302131 in the shape of "H" with double rows (width 1.05 m) and pile length 6.0 m are respectively constructed, the two ends of which respectively abut the outer layer rectangular cement mixing pile retaining wall 30211 and the inner layer rectangular cement mixing pile retaining wall 30212, and part of which respectively abut the adjacent cast-in-place piles 2. Similarly, in actual construction, on the top surface of the silt soft soil layer 1 at the left upper corner and the left lower corner of the outer layer rectangular cement mixing pile retaining wall 30211 adjacent to the left half of the foundation pit in the bridge direction, a plurality of rows of cement mixing piles with pile length 6.0 m are respectively constructed, and a plurality of cement mixing piles are connected to each other in the longitudinal direction and the transverse direction to form a full-area cement mixing pile retaining wall 302132, which respectively abuts the outer layer rectangular cement mixing pile retaining wall 30211 and the inner layer rectangular cement mixing pile retaining wall 30212. On the top surface of the silt soft soil layer at the right upper corner and the right lower corner of the outer layer rectangular cement mixing pile retaining wall 30211 adjacent to the right half of the foundation pit in the bridge direction, a plurality of rows of cement mixing piles with pile length 6.0 m are respectively constructed, and a plurality of cement mixing piles are connected to each other in the longitudinal direction and the transverse direction to form a full-area cement mixing pile retaining wall 302132, which respectively abuts the outer layer rectangular cement mixing pile retaining wall 30211 and the inner layer rectangular cement mixing pile retaining wall 30212. Similarly, in actual construction, on the top surface of the silt soft soil layer 1 at the intermediate position between the outer layer rectangular cement mixing pile retaining wall 30211 and the inner layer rectangular cement mixing pile retaining wall 30212 of the two length sides of the foundation pit, a plurality of cement mixing piles with double rows (width 1.05 m) and pile length 6.0 m are respectively constructed, and a plurality of cement mixing piles are connected to each other in the longitudinal direction and the transverse direction to form a one-shaped cement mixing pile retaining wall 302133, which respectively abuts the two cast-in-place piles 2 in the middle of the foundation pit.
[0045] Optionally, as Figure 1 and Figure 2As shown, the number of steel pipe inner supports 5 is two layers, the two layers of steel pipe inner supports 5 are arranged in parallel and spaced apart in space, and each layer of steel pipe inner supports 5 includes a plurality of straight steel pipe inner supports 501 and a plurality of inclined steel pipe inner supports 502. The plurality of inclined steel pipe inner supports 502 are arranged at the two ends of the deep foundation pit, and the two ends of each inclined steel pipe inner support 502 are respectively connected to the inner side walls of the adjacent two steel sheet pile enclosure walls 4. The plurality of straight steel pipe inner supports 501 are arranged between the inclined steel pipe inner supports 502 arranged at the two ends of the deep foundation pit in the length direction of the deep foundation pit, and are sequentially and spaced apart in the length direction of the deep foundation pit, and the two ends of each straight steel pipe inner support 501 are respectively connected to the inner side walls of the two opposite steel sheet pile enclosure walls 4 in the length direction of the deep foundation pit.
[0046] In this optional solution, as shown in Figure 1 and Figure 2 , the straight steel pipe inner support 501 and the inclined steel pipe inner support 502 are arranged in the same structure, and the straight steel pipe inner support 501 includes two steel enclosures 5012 fixed to the inner side walls of the two opposite steel sheet pile enclosure walls 4 in the length direction of the deep foundation pit, steel corbels 5011 connected between each steel enclosure 5012 and the inner side wall of the corresponding steel sheet pile enclosure wall 4, and steel pipe support rods 5013 connected between the two steel enclosures 5012. In this optional solution, the steel corbels 5011, the steel enclosures 5012, and the steel pipe support rods 5013 are all made of purchased semi-finished products and assembled and welded on site. The steel corbels 5011 are made of I25a H-shaped steel and welded with the inner side wall of the steel sheet pile enclosure wall 4 to form a triangular support frame; the steel pipe support rod 5013 is composed of a support rod system and an accessory component, wherein the support rod system includes a steel pipe main rod, a movable end, and a fixed end, and the accessory component includes a flange, high-strength bolts, and steel wedges, etc. The steel pipe main rod is composed of multiple steel pipes connected by flanges and high-strength bolts; the upper steel enclosure 5012 is made of Q235 and 3I5 56a H-shaped steel, the steel pipe used in the straight steel pipe inner support 501 is φ630*10mm steel pipe, and the steel pipe used in the inclined steel pipe inner support 502 is φ480*8mm steel pipe; the lower steel enclosure 5012 is made of Q235 and 3HN700*300 H-shaped steel, the steel pipe used in the straight steel pipe inner support 501 is φ1000*12mm steel pipe, and the steel pipe used in the inclined steel pipe inner support 502 is φ480*8mm steel pipe; the steel enclosure 5012 is cut according to the use position before processing, and is classified and neatly stacked according to the cutting table; the end face of all the directly bearing steel plates of the steel enclosure 5012 is pre-milled flat; the connection between the steel enclosure 5012 segments must be butt welded to lengthen by using equal strength connection method during the assembly of the steel enclosure 5012.
[0047] Alternatively, as shown in Figure 2 and 4As shown in the figure, the deep foundation pit composite support structure further comprises a pit outside cement mixing pile retaining wall 301 for reinforcing the silt soft soil layer 1 outside the deep foundation pit, the pit outside cement mixing pile retaining wall 301 is arranged along the circumference of the deep foundation pit and closely adheres to the outer side wall of the steel sheet pile retaining wall 4, and the pit outside cement mixing pile retaining wall 301 and the pit inside cement mixing pile retaining wall 302 jointly form a cement mixing pile retaining wall 3 to reinforce the silt soft soil layer 1. In the deep foundation pit composite support structure of the utility model, the pit bottom sealing concrete layer 6 in the foundation pit, the rectangular-like cement mixing pile retaining wall 3021, the straight support cement mixing pile retaining wall 3022, the pit outside cement mixing pile retaining wall 301, the steel sheet pile retaining wall 4 and the upper and lower two layers of steel pipe inner support 5 constitute a steel pipe concrete support structure, compared with the traditional foundation pit support method, the steel pipe concrete support structure can effectively enhance the rigidity of the deep foundation pit support structure, resist the sliding and collapse instability of the soil body of the side wall around the foundation pit; in the novel structure, the rectangular-like cement mixing pile retaining wall 3021, the straight support cement mixing pile retaining wall 3022, the pit bottom sealing concrete layer 6, the steel sheet pile retaining wall 4 and the pit outside cement mixing pile retaining wall 301 constitute a rectangular "water cup" type waterproof structure, compared with the traditional foundation pit support method, the novel structure can effectively prevent the underground water from seeping into the foundation pit or the construction sewage in the foundation pit from seeping out of the foundation pit to the nearby river, thereby improving the water stopping performance of the silt soft soil layer 1; in the novel structure, the straight support cement mixing pile retaining wall 3022 is constructed on the top surface of the silt soft soil layer 1 inside the steel sheet pile retaining wall 4 at the middle position of the length side of the foundation pit towards the center side of the foundation pit, and forms a rectangular "frame" type rigid anti-floating structure with the rectangular-like cement mixing pile retaining wall 3021 and the pit bottom sealing concrete layer 6, compared with the traditional foundation pit support method, the novel structure can effectively increase the weight of the bottom sealing component of the foundation pit, prevent the silt soft soil body layer at the bottom of the foundation pit from rising and gushing accidents, thereby improving the anti-uplift safety factor of the silt soft soil body at the bottom of the foundation pit.
[0048] As shown in the figure, Figure 2 Figure 2 As shown in the figure, the top elevation of the pit outside cement mixing pile retaining wall 301 is lower than the top elevation of the steel sheet pile retaining wall 4, and the bottom elevation of the pit outside cement mixing pile retaining wall 301 is lower than the top elevation of the pit inside cement mixing pile retaining wall 302, so that the pit outside cement mixing pile retaining wall 301 and the pit inside cement mixing pile retaining wall 302 partially overlap in the vertical direction. In the novel structure, the pit inside cement mixing pile retaining wall 302 is constructed on the top surface of the silt soft soil layer 1 inside the steel sheet pile retaining wall 4 at the middle position of the length side of the foundation pit towards the center side of the foundation pit, and the top elevation of the pit inside cement mixing pile retaining wall 302 is 0.5 m higher than the bottom elevation of the pit outside cement mixing pile retaining wall 301, so as to form a rectangular "sleeve" type silt soft soil reinforcing structure with a vertical overlap of 0.5 m, weaken the stress concentration of the steel sheet pile retaining wall 4 at the junction of the foundation pit bottom and the silt soft soil layer, and enhance the rigidity of the steel sheet pile retaining wall 4.
[0049] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A deep foundation pit composite support structure, characterized in that: include: A steel sheet pile retaining wall (4) for forming a temporary circumferential wall of a deep foundation pit, an outer cement mixing pile retaining wall (301) for reinforcing a silt soft soil layer (1) outside the deep foundation pit, an inner cement mixing pile retaining wall (302) and a plurality of cast-in-place piles (2) for reinforcing a silt soft soil layer (1) below the deep foundation pit, a bottom sealing concrete layer (6) for forming a bottom plate of the deep foundation pit, and a steel pipe inner support (5) for providing support within the deep foundation pit; The steel sheet pile retaining wall (4) is extended along the perimeter of the deep foundation pit and vertically extends into the silt soft soil layer (1) below the deep foundation pit; A plurality of cast-in-place piles (2) are dispersed and vertically extended downward into the silt soft soil layer (1) below the deep foundation pit; an outer cement mixing pile retaining wall (301) is arranged in the silt soft soil layer (1) outside the deep foundation pit and is closely attached to the outer side wall of the steel sheet pile retaining wall (4); an inner cement mixing pile retaining wall (302) is arranged in the silt soft soil layer (1) below the deep foundation pit and is closely attached to the inner side wall of the steel sheet pile retaining wall (4) and avoids the setting of the cast-in-place piles (2); and a bottom sealing concrete layer (6) is arranged on the top of the inner cement mixing pile retaining wall (302); The steel pipe inner support (5) is tightly supported between two opposite steel sheet pile retaining walls (4) and between two adjacent steel sheet pile retaining walls (4).
2. The deep foundation pit composite support structure according to claim 1, characterized in that: The bottom elevation of the cement mixing pile retaining wall (302) in the pit is higher than the bottom elevation of the steel sheet pile retaining wall (4), and the bottom elevation of the steel sheet pile retaining wall (4) is higher than the bottom elevation of the cast-in-place pile (2).
3. The deep foundation pit composite support structure according to claim 1, characterized in that: A plurality of cast-in-place piles (2) are evenly spaced and arranged at both ends of the deep foundation pit in the longitudinal direction, and the top of each cast-in-place pile (2) extends upward through the cement mixing pile retaining wall (302) and the bottom sealing concrete layer (6) in the pit, so as to be extended into a foundation pile poured in the deep foundation pit at a later stage; The top elevation of the plurality of cast-in-place piles (2) is higher than the top elevation of the cement mixing pile retaining wall (302) in the pit, and the top elevation of the plurality of cast-in-place piles (2) is higher than the top elevation of the bottom concrete layer (6); The bottom elevation of the bottom sealing concrete layer (6) is higher than the bottom elevation of the cement mixing pile retaining wall (301) outside the pit, and the bottom elevation of the bottom sealing concrete layer (6) is the same as the top elevation of the cement mixing pile retaining wall (302) inside the pit.
4. The deep foundation pit composite support structure according to claim 1, characterized in that: The cement mixing pile retaining wall (302) in the pit includes a hollow frame type rectangular cement mixing pile retaining wall (3021) and a multi-faceted straight support cement mixing pile retaining wall (3022); The multi-faceted straight-support cement mixing pile enclosure walls (3022) are arranged in sequence along the length direction of the rectangular cement mixing pile enclosure wall (3021), and the two sides of each straight-support cement mixing pile enclosure wall (3022) in the width direction are respectively connected to the rectangular cement mixing pile enclosure wall (3021).
5. The deep foundation pit composite support structure according to claim 4, characterized in that: The quasi-rectangular cement mixing pile enclosure wall (3021) comprises an inner rectangular cement mixing pile enclosure wall (30212) and an outer rectangular cement mixing pile enclosure wall (30211) which are arranged in an interval, and a special-shaped cement mixing pile enclosure wall (30213) connected therebetween. The outer rectangular cement mixing pile retaining wall (30211) is arranged along the circumference of the deep foundation pit and is closely attached to the inner side wall of the steel sheet pile retaining wall (4); Both ends of the straight support cement mixing pile enclosure wall (3022) along the width direction are respectively connected to the inner rectangular cement mixing pile enclosure wall (30212), the outer rectangular cement mixing pile enclosure wall (30211) and the special-shaped cement mixing pile enclosure wall (30213).
6. The deep foundation pit composite support structure according to claim 5, characterized in that: The special-shaped cement mixing pile retaining wall (30213) comprises an H-shaped cement mixing pile retaining wall (302131) connected at both ends of the deep foundation pit in the longitudinal direction and located between two adjacent cast-in-place piles (2) in the outermost layer, a quasi-full-area cement mixing pile retaining wall (302132) connected at each vertex between the outer rectangular cement mixing pile retaining wall (30211) and the inner rectangular cement mixing pile retaining wall (30212), and a straight-shaped cement mixing pile retaining wall (302133) connected between two adjacent straight-support cement mixing pile retaining walls (3022).
7. The deep foundation pit composite support structure according to claim 1, characterized in that: The number of the steel tube inner supports (5) is two layers, the two layers of steel tube inner supports (5) are spaced apart and arranged in parallel up and down, and each layer of steel tube inner supports (5) includes a plurality of straight steel tube inner supports (501) and a plurality of inclined steel tube inner supports (502); A plurality of inclined steel pipe inner supports (502) are respectively arranged at both ends of the deep foundation pit, and both ends of each inclined steel pipe inner support (502) are respectively connected to the inner side walls of two adjacent steel sheet pile retaining walls (4); A plurality of straight steel pipe inner supports (501) are arranged between the inclined steel pipe inner supports (502) provided at both ends in the longitudinal direction of the deep foundation pit, and are sequentially spaced along the longitudinal direction of the deep foundation pit, and the two ends of each straight steel pipe inner support (501) are respectively connected to the inner side walls of two opposite steel sheet pile retaining walls (4) in the longitudinal direction of the deep foundation pit.
8. The deep foundation pit composite support structure according to claim 7, characterized in that: The straight steel tube inner support (501) and the inclined steel tube inner support (502) have the same structural arrangement. The straight steel tube inner support (501) includes: Two steel purlins (5012) fixed on the inner side walls of two opposite steel sheet pile retaining walls (4) in the length direction of the deep foundation pit, a steel corbel (5011) connected between each steel purlin (5012) and the inner side wall of the corresponding steel sheet pile retaining wall (4), and a steel pipe support rod (5013) connected between the two steel purlins (5012).
9. The deep foundation pit composite support structure according to claim 1, characterized in that: The deep foundation pit composite support structure further comprises an outside-pit cement mixing pile retaining wall (301) for reinforcing the silt soft soil layer (1) outside the deep foundation pit. The outside-pit cement mixing pile retaining wall (301) is arranged along the circumference of the deep foundation pit and is closely attached to the outer side wall of the steel sheet pile retaining wall (4).
10. The deep foundation pit composite support structure according to claim 9, characterized in that: The top elevation of the cement mixing pile retaining wall (301) outside the pit is lower than the top elevation of the steel sheet pile retaining wall (4), and the bottom elevation of the cement mixing pile retaining wall (301) outside the pit is lower than the top elevation of the cement mixing pile retaining wall (302) inside the pit, so that the cement mixing pile retaining wall (301) outside the pit and the cement mixing pile retaining wall (302) inside the pit partially overlap in the vertical direction.