Deep foundation pit excavation method under complex geological conditions and auxiliary device

Abstract

The invention belongs to the technical field of building construction, and particularly discloses a deep foundation pit excavation method and an auxiliary device under complex geological conditions, the auxiliary device comprises at least two hanging bars, a supporting plate and a positioning baffle, through holes are coaxially formed in the supporting plate and the positioning baffle, one end of each hanging bar is connected with the supporting plate, and the other end of each hanging bar is connected with the positioning baffle. The length of the portion, stretching into the pile hole, of each hanging bar is the depth between the top of the foundation pile and an orifice of the pile hole of the foundation pile, and the supporting plate is fixed to the orifice of the pile hole of the foundation pile in a limited mode. The deep foundation pit excavation method comprises the following steps that surface layer soil of a construction area is cleaned, and the surface layer of the construction area is leveled; constructing a fender post on one side of the pre-excavation position of the foundation pit, and constructing a foundation pile at the pre-excavation position of the foundation pit by using an auxiliary device; a foundation trench is excavated in the foundation pit pre-excavation position to form a stilling pool foundation pit shape; and after the stilling pool foundation pit is excavated and formed, concrete is poured into the foundation pit to form a stilling pool structure. The construction difficulty can be reduced, and the pile body quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building construction, in particular to a deep foundation pit excavation method and auxiliary device under complex geological conditions. BACKGROUND

[0002] In ordinary water conservancy projects, deep foundation pit construction tries to avoid flood season, and the excavation of the foundation trench is mainly for rock foundation, and the slope stability is good. However, in the main flood season, deep foundation pit construction is mainly done by protecting the slope, such as steel sheet pile, soil nailing wall, etc. Deep foundation pit construction during flood season is less. For deep foundation pit excavation during flood season, the water source is abundant in the foundation pit area, and the geology is mainly soft geology. It is a difficulty to ensure safety, efficiency and speed in such a situation.

[0003] The construction content of the deep foundation pit of the stilling basin mainly includes the cofferdam pile, the excavation of the foundation trench of the stilling basin, the foundation pile in the foundation trench of the stilling basin, and the structure concrete of the stilling basin. The traditional construction process is: cofferdam pile construction -- foundation pit drainage -- deep foundation pit excavation -- foundation pile construction -- structure concrete construction, that is, after the excavation of the foundation pit, the foundation pile is constructed in the foundation pit; When constructing the foundation pile, a hole is drilled in the foundation trench to form a pile hole for pouring the foundation pile in the later stage, and then a reinforcement cage is lowered into the pile hole in the foundation pile. Usually, the reinforcement cage needs to be pre-processed into multiple sections and installed and hoisted in sections at the construction site. Specifically, the last section of the reinforcement cage is supported at the opening of the pile hole by a support bracket, the next section of the reinforcement cage is welded and fixed to the top of the last section of the reinforcement cage by a sleeve to form an integral whole, and then the support bracket is removed, so that the reinforcement cage connected as a whole is hoisted downward. The multiple sections of the reinforcement cage are sequentially welded and fixed and then hoisted downward to complete the fixation of the multiple sections of the reinforcement cage. Finally, the concrete is poured into the pile hole to form the foundation pile.

[0004] In the above construction method of the foundation pile, since the foundation pile is constructed in the foundation trench after the excavation of the foundation trench, this method has the following defects: 1) The site in the foundation trench is narrow, and it is difficult for the pile construction equipment to enter the foundation pit after the excavation of the foundation pit, which is not conducive to the arrangement of temporary facilities and slurry discharge equipment, and the construction difficulty is increased. Since the traditional construction process constructs the pile body in the foundation pit, the working surface is narrow, and the pile drilling equipment, mud equipment, reinforcement cage hoisting, and concrete pouring are not easy to control, the pile quality control during construction is poor, the construction difficulty is large, and the construction efficiency is low.

[0005] 2) If the foundation trench construction is in the main flood season, the exposed time of the foundation trench after construction is long, and there may be safety risks such as flooding, foundation trench and slope instability.

[0006] 3) When the deep foundation pit of the stilling basin is excavated during the flood season, the groundwater is abundant, and the difficulty of dewatering is increased. SUMMARY

[0007] The application provides a deep foundation pit excavation method and auxiliary device under complex geological conditions, which aims to reduce the construction difficulty and improve the pile quality.

[0008] The application is realized by the following technical scheme: The application provides a deep foundation pit excavation auxiliary device under complex geological conditions, which assists in the construction of foundation piles, characterized by comprising a hanging rib, a supporting plate and a positioning baffle, wherein coaxial through holes are formed in the supporting plate and the positioning baffle, at least two hanging ribs are provided, one end of each of the hanging ribs is connected to the supporting plate, and the other end of each of the hanging ribs is connected to the positioning baffle, the length of the hanging rib extending into the pile hole is the depth between the top of the foundation pile and the pile hole opening of the foundation pile, and the supporting plate is fixed at the pile hole opening of the foundation pile.

[0009] Beneficial effects: the length of the hanging rib extending into the pile hole is the depth between the top of the foundation pile and the pile hole opening of the foundation pile, and the supporting plate is limited and fixed on the surface layer, so that the lowering position and elevation of the foundation pile reinforcement cage can be accurately controlled. Under complex geological conditions, the fluctuation of the stratum or the construction error can easily cause the pile position to deviate, the device fixes the length of the hanging rib to ensure that the top of the reinforcement cage coincides with the design elevation, avoids the problems of excessive depth or excessive shallowness, ensures that the elevations of the constructed foundation piles are consistent, the quality of the concrete structure of the foundation pit in the later construction is higher, the length of the empty pile at the upper part of the foundation pile can be controlled (i.e., it is ensured that there is no foundation pile in the foundation groove to be excavated later), the construction quality of the foundation pile is ensured, the pouring engineering quantity and construction cost are effectively controlled, the auxiliary tool in the present application can make it unnecessary to process the foundation pile after the pouring is completed, i.e., it can meet the requirement that there is no protruding foundation pile in the foundation groove, the construction efficiency and cost are improved, and the construction difficulty is effectively reduced. The present application makes the foundation pile a finished product after the construction is completed, and it is not necessary to cut the foundation pile to ensure its effective elevation after the foundation groove is excavated.

[0010] In addition, the multiple hanging ribs, the supporting plate and the positioning baffle form a stable suspension support system in the present application, which effectively prevents the reinforcement cage from floating or tilting during the concrete pouring process, and ensures the stability of the reinforcement cage. In complex geology, factors such as fluctuation of mud density and uneven pouring speed can easily cause the reinforcement cage to shift, the device provides reliable constraints through rigid connection to ensure that the reinforcement cage always stays at the designed position, and protects the thickness of the reinforcement cage and the structure stress performance.

[0011] The positioning baffle in the present application can ensure the flatness of the top of the poured foundation pile, improve the construction quality of the foundation pile, and play a positioning role in the pouring elevation of the foundation pile to ensure that the elevations of the multiple foundation piles formed by pouring are basically at the same position.

[0012] Further, the hanging ribs are detachably connected with the positioning baffle.

[0013] Beneficial effects: in this scheme, the hanging ribs can be conveniently removed after the foundation pile construction is completed, without affecting the normal excavation of the foundation trench.

[0014] Further, a plurality of connecting barrels are provided, which are sequentially arranged opposite to the plurality of hanging ribs, and the connecting barrels are connected with the positioning baffle, one end of the connecting barrel is detachably connected with the hanging rib, and the other end of the connecting barrel is inserted into the top of the reinforcement cage of the foundation pile and connected with the reinforcement cage.

[0015] Beneficial effects: in this scheme, the connecting barrel is connected with the top of the reinforcement cage of the foundation pile, thereby improving the axial limiting effect of the reinforcement cage as a whole, keeping the reinforcement cage in a stable state, and further improving the verticality of the foundation pile pouring forming, thereby improving the construction quality of the foundation pile.

[0016] The connecting barrel and the hanging rib are detachably connected, so that the hanging rib can be removed after the foundation pile is poured, avoiding affecting the excavation of the foundation trench.

[0017] Further, the two ends of the positioning baffle are in contact with the sidewall of the pile hole of the foundation pile and can vertically slide along the pile hole of the foundation pile, the connecting barrel comprises an upper barrel and a lower barrel, and the upper barrel and the lower barrel are respectively connected with the top and bottom of the positioning baffle; the hanging rib is detachably connected with the upper barrel, and the lower barrel is inserted into the top of the reinforcement cage of the foundation pile and connected with the reinforcement cage.

[0018] Beneficial effects: in this scheme, the two ends of the positioning baffle are in contact with the sidewall of the pile hole drilled in the foundation pile, so that the positioning baffle has a limiting effect on the concrete in the pouring process, avoiding the overflow of the concrete from the gap between the positioning baffle and the pile hole of the foundation pile upward, and affecting the quality and elevation of the finally formed foundation pile.

[0019] The two ends of the positioning baffle are in close contact with the sidewall of the pile hole and can vertically slide, forming a dynamic guiding constraint, which can correct the deviation of the reinforcement cage during the lowering process, and ensure that it always falls vertically along the center line of the pile hole.

[0020] Further, a protection barrel is provided, which is inserted into the pile hole for pouring the foundation pile, at least two guide grooves are formed on the protection barrel along the axial direction, a sliding block is fixedly connected to the outer side of the positioning baffle, the number of the sliding blocks is the same as that of the guide grooves, and the sliding blocks can be inserted into and slid along the guide grooves.

[0021] Beneficial effects: The setting of the protection sleeve in the scheme can support the pile hole, avoid the collapse of the soil on the side wall of the pile hole and affect the hole forming, in addition, the guide groove on the protection sleeve and the sliding block on the outer side of the connecting sleeve are in sliding fit, which can guide the downward movement of the hanging reinforcement, ensure the stability of the downward movement of the hanging reinforcement, and avoid the deviation of the hanging reinforcement, thereby improving the positioning effect of the reinforcement cage.

[0022] And in the later stage, the hanging reinforcement and the positioning baffle can be taken out together in the process of taking out the protection sleeve, improving the work efficiency and reducing the cost.

[0023] A deep foundation pit excavation method under complex geological conditions, comprising the following steps: Step one, clean up the surface layer of the construction area, and flatten the surface layer of the construction area; Step two, construction of a retaining pile on one side of the foundation pit pre-excavation position, and construction of a foundation pile at the foundation pit pre-excavation position using an auxiliary device for deep foundation pit excavation under complex geological conditions according to any one of claims 1-5; Step three, excavate a foundation trench at the foundation pit pre-excavation position to form a stilling basin foundation pit shape; Step four, after the stilling basin foundation pit is excavated and formed, pour concrete in the foundation pit to form a stilling basin structure.

[0024] Compared with the prior art, the scheme has the following advantages and beneficial effects: In the scheme, the retaining pile and the foundation pile are constructed before the foundation trench of the foundation pit is opened, and the foundation trench of the foundation pit is excavated after the construction of the retaining pile and the foundation pile is completed. In this way, during the construction of the retaining pile and the foundation pile, the construction can be carried out on the original ground, the construction operation area is wider, the construction difficulty is effectively reduced, and the pile body quality control of the cast-in-place pile (retaining pile and foundation pile) is better. In addition, the wide construction area operation is more convenient, and the construction efficiency is higher. Furthermore, the wide original ground working environment also provides a safer operation space for construction personnel and equipment, reducing the probability of accidents such as high-altitude falling and mechanical collision.

[0025] In terms of cost, the construction resources of the retaining pile and the foundation pile are concentratedly utilized in the scheme, improving the utilization rate of the equipment and reducing the construction cost.

[0026] In addition, in the scheme, the foundation trench of the foundation pit is excavated after the construction of the retaining pile and the foundation pile is completed, so that the long exposure time of the excavated foundation trench after the construction of the foundation pile is avoided, and if the foundation trench is exposed for a long time, the construction of the foundation pile during the main flood season can easily increase the exposure time of the foundation trench of the foundation pit, thereby easily increasing the safety risk. The construction of the foundation pile in advance can avoid the long exposure of the foundation trench of the foundation pit, and effectively reduce the safety hazards such as landslides and water gushing caused by rainfall, underground water changes and other factors. Especially during the main flood season, the completion of the foundation pile construction in advance can greatly reduce the exposure time of the foundation pit and reduce the emergency rescue cost. After the construction of the retaining pile and the foundation pile is completed, the mud cleaning and equipment withdrawal can be immediately carried out, which can provide space for subsequent foundation trench excavation and significantly improve the construction organization efficiency.

[0027] Under complex geological conditions (such as soft soil, sand layer, karst and other special strata), the retaining pile and the foundation pile constructed in advance form a three-dimensional support system, which can effectively resist the lateral pressure of the soil and the seepage force of the underground water, and avoid accidents such as foundation pit collapse and quicksand caused by geological mutations. At the same time, the construction of the foundation pile in advance can accurately position the bearing stratum, ensure that the bearing capacity of the pile foundation meets the design requirements, and improve the long-term stability of the overall structure of the deep foundation pit.

[0028] Further, in step one, stone slag is laid on the surface layer of the construction area.

[0029] Beneficial effects: In the scheme, the original surface layer is cleaned and leveled before construction, and stone slag is laid, which is beneficial to the compaction and reinforcement of the soil at the foundation trench position, the discharge of underground water at the foundation trench, and the subsequent excavation of the foundation trench.

[0030] Further, in step three, the water is discharged during the excavation process, and a water collecting well and a drainage ditch are arranged in the foundation pit, and the water in the water collecting well is pumped out of the foundation pit by a water pump; the drainage ditch is excavated around the bottom of the foundation pit or in the center, a plurality of water collecting wells are arranged in the foundation pit, and one end of the drainage ditch leads into the water collecting well.

[0031] Beneficial effects: Under complex geological conditions, when the underground water is abundant or the water level is high, the open drainage can quickly reduce the water level in the foundation pit, effectively reduce the seepage pressure of the underground water on the soil of the pit wall, prevent phenomena such as quicksand and piping, and avoid the collapse of the side wall of the foundation pit, thereby creating a safe working environment for construction personnel and equipment.

[0032] By timely discharging the accumulated water in the foundation pit, the softening of the soil at the bottom of the foundation pit due to water immersion can be prevented, the soil at the bottom of the foundation pit can be kept dry and firm, the subsequent foundation construction (such as concrete pouring of the stilling basin) can be carried out on the foundation that meets the design requirements, and the bearing capacity and durability of the engineering structure can be ensured.

[0033] The open drainage system can make the foundation pit excavation continuous operation, without frequent interruption of construction due to accumulated water, and shorten the construction period. At the same time, the dry working surface facilitates the operation of excavators, bulldozers and other equipment, reduces the running resistance and failure probability of equipment in the muddy environment, and improves the mechanical operation efficiency.

[0034] The water collecting well and the drainage ditch are flexible in setting, and can be adjusted in layout according to the shape, size and geological changes of the foundation pit. They can be quickly deployed and play a role under different complex geological conditions, have strong universality and environmental adaptability, and ensure stable and reliable dewatering effect.

[0035] In the scheme, the drainage ditch is excavated around or in the center of the bottom of the foundation pit, and one end of the drainage ditch is introduced into the water collecting well, thereby constructing a drainage network connected by the ditch and the well. This layout can make the accumulated water in the foundation pit quickly flow into the water collecting well through the drainage ditch, reduce the residence time of the accumulated water in the bottom of the foundation pit, avoid the immersion and softening of the soil at the bottom of the foundation pit due to the accumulated water, and ensure the continuity of the foundation pit excavation and subsequent construction.

[0036] The specific drainage ditch path design in the scheme can guide the water flow in the foundation pit to flow in the planned direction, avoid the water flow from washing the side wall of the foundation pit in disorder, reduce the risk of pit wall collapse caused by water flow erosion. At the same time, the water is concentrated and drained to the water collecting well, which is convenient for unified management and pumping, reduces the interference to the construction area during the drainage process, and provides a safe working environment for the construction personnel and equipment.

[0037] Further, in step two, when the foundation pile is constructed, the effective elevation of the foundation pile is located below the surface layer of the construction area; The top end of the topmost section of the reinforcement cage of the foundation pile is fixed with the positioning baffle, and then the auxiliary device is hoisted downward as a whole, so that the topmost section of the reinforcement cage of the foundation pile is hoisted downward synchronously, until the support plate is limited on the pile hole opening of the foundation pile, at which time the hoisting of the reinforcement cage of the foundation pile is completed; When the concrete is poured in the pile hole of the foundation pile to the position of the positioning baffle, the pouring is stopped, and the distance between the positioning baffle and the support plate is the empty pile part of the foundation pile.

[0038] Beneficial effects: In the scheme, the distance between the positioning baffle and the support plate is the empty pile part of the foundation pile, so that the top of the formed foundation pile and the surface layer of the construction area form an empty pile, i.e. the foundation pile is not located in the foundation trench during the excavation of the foundation trench in the later stage, so that the foundation pile can be eliminated during the excavation of the foundation trench in the later stage; at the same time, there is no foundation pile in the excavated foundation trench, which reduces the step of processing the foundation pile in the foundation trench in the later stage, thereby improving the construction efficiency and simplifying the construction process, and the construction method of the scheme can effectively reduce the cost of pouring the foundation pile and reduce the amount of poured concrete.

[0039] Further, in step two, in the process of constructing the retaining pile, a percussion drill is used to form a hole, and mud is used to protect the wall, the retaining pile construction has multiple, multiple retaining piles are arranged in a single row, and there is a spacing between the adjacent two retaining piles, and a crown beam is constructed at the top of the retaining pile.

[0040] Beneficial effects: under the complex geological conditions of soft geology, if a rotary drilling rig is used for drilling, the hole collapse is frequent, and the stringing hole between the holes is more, which leads to the mixing of pile concrete into the adjacent pile hole, and the adjacent pile is difficult to form a hole.

[0041] In the present scheme, the rotary drilling rig is adjusted to a percussion drill, mud is used to protect the wall, and the hole collapse and stringing hole are reduced to ensure the quality of hole forming.

[0042] In addition, multiple retaining piles are arranged in a single row and have a spacing, which reduces the number of piles compared with dense piles, reduces the amount of steel, concrete and other materials, and reduces the mechanical hole forming workload, directly saving the construction cost. At the same time, the spacing design provides more flexible operation space for construction machinery, facilitates the movement of the drill, the hoisting of the reinforcement cage and the pouring of concrete, reduces the process interference, improves the construction efficiency, and shortens the construction period. The multiple retaining piles arranged in a single row in the present scheme have a spacing between the adjacent two retaining piles, which can reduce the situation that the pile concrete is mixed into the adjacent pile hole, and ensure the forming quality of the pile. BRIEF DESCRIPTION OF DRAWINGS

[0043] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings: Figure 1 is a longitudinal sectional view of one embodiment of the deep foundation pit excavation auxiliary device under complex geological conditions of the present application; Figure 2 is a bottom view of the support plate and the hanging reinforcement in the embodiment of the deep foundation pit excavation auxiliary device under complex geological conditions of the present application; Figure 3 is Figure 1 is a local enlarged view of A in the middle; Figure 4 is a top view of the positioning baffle and the connecting cylinder in one embodiment of the deep foundation pit excavation auxiliary device under complex geological conditions of the present application; Figure 5 is a longitudinal sectional view of another embodiment of the deep foundation pit excavation auxiliary device under complex geological conditions of the present application; Figure 6 is Figure 5 is a local enlarged view of B in the middle; Figure 7 is a top view of the positioning baffle and the connecting cylinder in another embodiment of the deep foundation pit excavation auxiliary device under complex geological conditions of the present application; Figure 8 is a longitudinal sectional view of the embodiment of the auxiliary device for deep foundation pit excavation under complex geological conditions of the application after the casing is arranged; Figure 9 is Figure 8 is a local enlarged view at C; Figure 10 is a sectional view of the foundation pile, the retaining pile and the stilling basin structure in construction in the method for deep foundation pit excavation under complex geological conditions of the application.

[0044] Markings in the drawings and corresponding names of parts: foundation pile 1, retaining pile 2, ground surface layer 3, foundation pit 4, stilling basin structure 5, casing 6, guide groove 60, reinforcement cage 7, hanging reinforcement 8, support plate 9, connecting cylinder 10, upper cylinder 101, lower cylinder 102, positioning baffle 11, sliding block 110, pressure sensor 12. DETAILED DESCRIPTION

[0045] To make the purpose, technical solutions and advantages of the application clearer and more apparent, the application is further described in detail below with reference to the embodiments and drawings, the illustrative embodiments of the application and the description thereof are only used to explain the application and do not limit the application.

[0046] As Figures 1-2 shown, as an embodiment of the application, an auxiliary device for deep foundation pit 4 excavation under complex geological conditions is provided for assisting in construction of a foundation pile 1, which comprises a hanging reinforcement 8, a support plate 9 and a positioning baffle 11, and a through hole is coaxially arranged on the support plate 9 and the positioning baffle 11, which is used for inserting a guide pipe for pouring concrete later.

[0047] The hanging reinforcement 8 is provided with at least two, and in the embodiment, the hanging reinforcement 8 is provided with four, which are arranged in a rectangular array as Figure 2 shown, one end of the hanging reinforcement 8 is connected with the support plate 9, and the other end of the hanging reinforcement 8 is connected with the positioning baffle 11, the length of the hanging reinforcement 8 extending into the pile hole is the depth between the top of the foundation pile 1 and the pile hole opening of the foundation pile 1, and the support plate 9 is limited and fixed at the pile hole opening of the foundation pile 1, and in the embodiment, the support plate 9 is a circular plate, and the diameter of the support plate 9 is greater than the diameter of the pile hole of the foundation pile 1, so that when the support plate 9 is located at the pile hole opening, it can be blocked on the opening, thereby supporting the hanging reinforcement 8.

[0048] The positioning baffle 11 is connected to the top of the reinforcement cage 7 of the foundation pile 1 in this embodiment, thereby being connected to the auxiliary device in this embodiment as a whole, facilitating hoisting and supporting positioning. After the foundation pile 1 is poured, the hoisting reinforcement 8 can be separated from the positioning baffle 11 by cutting or other methods in the later stage. The auxiliary device of this embodiment can make the foundation pile 1 in the base trench part form an empty pile, reduce the pouring cost, and make the empty pile part of the foundation pile 1 more convenient to process in the later stage. The empty pile of the foundation pile 1 refers to the pile hole in the base trench part without pouring concrete.

[0049] In one embodiment, the hoisting reinforcement 8 is fixedly connected, such as welded, to the positioning baffle 11 and the supporting plate 9. When the positioning baffle 11 is connected to the reinforcement cage 7 in the later stage and the foundation pile 1 is poured, the positioning baffle 11 is separated from the hoisting reinforcement 8 by welding in the later stage after the base trench is excavated, so that the hoisting reinforcement 8 can be removed.

[0050] In another embodiment, the hoisting reinforcement 8 is detachably connected to the positioning baffle 11. Specifically, the hoisting reinforcement 8 is threadedly connected to the positioning baffle 11 in this embodiment, which facilitates assembly and makes it convenient to separate the hoisting reinforcement 8 from the positioning baffle 11 before the base trench is excavated, so that the hoisting reinforcement 8 is taken out, while the positioning baffle 11 remains at the top of the poured foundation pile 1. The positioning baffle 11 can serve as a positioning standard for the effective elevation of the pouring of the foundation pile 1. In this embodiment, the hoisting reinforcement 8 is also threadedly connected to the supporting plate 9, which facilitates rotating the hoisting reinforcement 8 and making the hoisting reinforcement 8 axially move to be detached from the positioning baffle 11, while the hoisting reinforcement 8 is connected to the supporting plate 9, so that the supporting plate 9 supports the hoisting reinforcement 8.

[0051] Meanwhile, the top end of the hoisting reinforcement 8 extends out of the supporting plate 9, which facilitates rotating the hoisting reinforcement 8 outside the pile hole to separate the hoisting reinforcement 8 from the positioning baffle 11.

[0052] In one embodiment, at least two symmetrical lifting lugs are installed at the top end of the supporting plate 9, which facilitates hoisting the entire device.

[0053] In one embodiment, as shown in Figure 1 and Figure 3 A deep foundation pit 4 excavation auxiliary device under complex geological conditions further includes a connecting cylinder 10. The number of the connecting cylinder 10 is the same as that of the hoisting reinforcement 8. Each connecting cylinder 10 is arranged opposite to each hoisting reinforcement 8 in sequence. The connecting cylinder 10 is connected to the positioning baffle 11. In combination with Figure 4 shown in the drawings, the connecting cylinder 10 is fixedly welded or integrally formed with the outer side of the positioning baffle 11 in this embodiment. One end of the connecting cylinder 10 is detachably connected to the hoisting reinforcement 8, and the other end of the connecting cylinder 10 is inserted into the top of the reinforcement cage 7 of the foundation pile 1 and connected to the reinforcement cage 7.

[0054] The bottom end of the hanging rib 8 is coaxially screwed with the upper part of the connecting cylinder 10 in this embodiment, and the lower part of the connecting cylinder 10 is welded and fixed with the reinforcement cage 7 of the foundation pile 1. Thus, after pouring the foundation pile 1, the hanging rib 8 and the supporting plate 9 can be removed, and the connecting cylinder 10 and the positioning baffle 11 form an integral part of the foundation pile 1. The positioning baffle 11 and the connecting cylinder 10 do not affect the excavation and pouring of the foundation trench, and since the foundation trench will be poured with concrete to form the stilling basin structure 5 later, the positioning baffle 11 and the connecting cylinder 10 are covered.

[0055] In one embodiment, in combination with Figure 5 and Figure 6 As shown in Figure 6 and Figure 7 The connecting cylinder 10 includes an upper cylinder 101 and a lower cylinder 102, and the upper cylinder 101 and the lower cylinder 102 are welded with the top and bottom of the positioning baffle 11, respectively. The hanging rib 8 is detachably connected with the upper cylinder 101, and in this embodiment, the hanging rib 8 is screwed with the upper cylinder 101. The lower cylinder 102 is inserted into the top of the reinforcement cage 7 of the foundation pile 1 and connected with the reinforcement cage 7.

[0056] In one embodiment, in combination with Figure 8 and Figure 9 As shown in

[0057] At least two guide grooves 60 are formed on the protective cylinder 6 along the axial direction thereof, and the outer side of the positioning baffle 11 is fixedly connected with sliding blocks 110. The number of the sliding blocks 110 is the same as that of the guide grooves 60, and the sliding blocks 110 can be inserted into the guide grooves 60 and can slide along the guide grooves 60. The top of the guide groove 60 penetrates the protective cylinder 6, and when the sliding block 110 slides to the bottom of the guide groove 60, it is in the lowered-in-place state.

[0058] In one embodiment, as shown in Figure 1 and Figure 3 A pressure sensor 12 is embedded on the positioning baffle 11. When the poured concrete reaches the positioning baffle 11, an extrusion force is generated on the positioning baffle 11, which is recognized by the pressure sensor 12. At this time, the pressure sensor 12 sends a signal to the central control system to pause the continuous pouring of concrete.

[0059] The pressure sensor 12 is used as a core detection element in this embodiment, which realizes pressure detection based on piezoresistive effect or piezoelectric effect. When the poured concrete reaches the positioning baffle 11, an extrusion force is generated on the positioning baffle 11, which is transmitted to the pressure sensor 12 embedded in the positioning baffle. Taking a piezoresistive pressure sensor as an example, the inside thereof is composed of a pressure-sensitive resistor in a Wheatstone bridge structure. When an external force is applied, the resistance value of the pressure-sensitive resistor changes, thereby breaking the balance state of the bridge and outputting a voltage signal in linear relationship with the pressure size. The piezoelectric pressure sensor converts the pressure signal into an electric signal by using the characteristic that certain crystal materials generate electric charges when subjected to pressure, so as to realize the sensing of the extrusion force of the concrete.

[0060] After the pressure sensor 12 converts the pressure signal into an electric signal, the electric signal is transmitted to the central control system through a signal transmission line. The central control system pre-sets a pressure threshold. When the received pressure signal data exceeds the threshold, it is determined that the concrete has reached the positioning baffle 11, and the central control system will immediately issue a control instruction to suspend the operation of the concrete pouring equipment, so as to realize the accurate control of the concrete pouring height.

[0061] In one embodiment, as shown in Figure 10 A deep foundation pit 4 excavation method under complex geological conditions includes the following steps: Step one, the surface layer 3 of the construction area is cleaned, the surface layer 3 is leveled, and a 30cm-thick stone slag material is paved on the surface layer 3 of the construction area and is compacted; Step two, a fender pile 2 is constructed on one side of the foundation pit 4 pre-excavation position, and a foundation pile 1 is constructed in the foundation pit 4 pre-excavation position using any one of the auxiliary devices for deep foundation pit 4 excavation under complex geological conditions in any one of the above embodiments; Step three, a foundation trench is excavated at the foundation pit 4 pre-excavation position to form a stilling basin foundation pit 4 shape; Step four, after the stilling basin foundation pit 4 is excavated and formed, concrete is poured in the foundation pit 4 to form a stilling basin structure 5.

[0062] In one embodiment, in step three, dewatering is performed during the excavation of the foundation trench, a water collecting well and a drainage ditch are arranged in the foundation pit 4, and water in the water collecting well is pumped out of the foundation pit 4 by a water pump; the drainage ditch is excavated around the bottom of the foundation pit 4 or in the center, a plurality of water collecting wells are arranged in the foundation pit 4, and one end of the drainage ditch leads into a water collecting well.

[0063] In one embodiment, in step two, when the fender pile 2 is constructed, a percussion drill is used to form a hole, and a mud wall is used for construction. The fender pile 2 is constructed in multiple, a plurality of fender piles 2 are arranged in a single row, and there is a spacing between adjacent two fender piles 2. The spacing between the fender piles 2 is greater than or equal to 5m, and a corbel is constructed on the top of the fender pile 2. In one embodiment, in step two, the effective height of the foundation pile 1 is located below the surface layer 3 of the construction area when the foundation pile 1 is constructed; In the surface layer 3 and at the position of the later excavated foundation trench, a pile hole of the foundation pile 1 is drilled according to the preset position of the foundation pile 1, and then a reinforcement cage 7 is lowered into the pile hole of the foundation pile 1. The complete reinforcement cage 7 is composed of multiple independent and prefabricated reinforcement cages 7. The reinforcement cage 7 at the lower layer is fixed at the opening of the pile hole by a support bracket and is welded and assembled with the reinforcement cage 7 at the upper layer, and then is lowered into the pile hole. This operation is repeated until the reinforcement cage 7 at the top of the foundation pile 1 is installed. After the last reinforcement cage 7 is fixed at the opening by the support bracket, the top of the reinforcement cage 7 at the top of the foundation pile 1 is fixed with the positioning baffle 11 in the deep foundation pit 4 excavation auxiliary device, and then the auxiliary device is continuously lowered to synchronously lower the reinforcement cage 7 at the top until the support plate 9 is positioned on the opening of the pile hole of the foundation pile 1. At this time, the reinforcement cage 7 of the foundation pile 1 is completed. When the concrete is poured into the pile hole of the foundation pile 1 to the position of the positioning baffle 11, the pouring is stopped. The distance between the positioning baffle 11 and the support plate 9 is the empty pile part of the foundation pile 1.

[0064] In practice, in order to ensure the stability of the installation, the support plate 9 can be fixed to the surface layer 3 by bolts.

[0065] It should be noted that the above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A deep foundation pit excavation auxiliary device under complex geological conditions, used to assist in the construction of foundation piles, characterized in that: It includes a hanging rod, a support plate and a positioning baffle, the support plate and the positioning baffle are coaxially provided with through holes, the hanging rod is provided with at least two, one end of the hanging rod is connected to the support plate, and the other end of the hanging rod is connected to the positioning baffle, the length of the hanging rod extending into the pile hole is the depth between the top of the foundation pile and the pile hole opening of the foundation pile, and the support plate is limited and fixed at the pile hole opening of the foundation pile.

2. The deep foundation pit excavation auxiliary device under complex geological conditions according to claim 1 is characterized in that: The hanging rod is detachably connected to the positioning baffle.

3. The deep foundation pit excavation auxiliary device under complex geological conditions according to claim 2 is characterized in that: It also includes connecting tubes, the number of which is the same as the number of the hanging bars, the connecting tubes are arranged opposite to the hanging bars in sequence, the connecting tubes are connected to the positioning baffle, one end of the connecting tube is detachable from the hanging bar, and the other end of the connecting tube is connected to the top of the steel cage inserted into the foundation pile and to the steel cage.

4. The auxiliary device for deep foundation pit excavation under complex geological conditions according to claim 3 is characterized in that: The two ends of the positioning baffle are in contact with the side walls of the pile hole of the foundation pile and can slide vertically along the pile hole of the foundation pile. The connecting tube includes an upper tube and a lower tube, and the upper tube and the lower tube are respectively connected to the top and bottom of the positioning baffle; the hanger is detachably connected to the upper tube, and the lower tube is inserted into the top of the steel cage of the foundation pile and connected to the steel cage.

5. The auxiliary device for deep foundation pit excavation under complex geological conditions according to any one of claims 2 to 4, characterized in that: It also includes a casing, which is inserted into a pile hole for pouring foundation piles. At least two guide grooves are opened on the casing along its axial direction. Sliders are fixedly connected to the outer side of the positioning baffle. The number of the slides is the same as that of the guide grooves, and the slides can be inserted into the guide grooves and can slide along the guide grooves.

6. A method for deep foundation pit excavation under complex geological conditions, characterized in that: The following steps are involved: Step 1: Clean the surface soil in the construction area and level the surface layer of the construction area; Step 2: constructing retaining piles on one side of the pre-excavation position of the foundation pit, and constructing foundation piles at the pre-excavation position of the foundation pit using the deep foundation pit excavation auxiliary device under complex geological conditions as described in any one of claims 1 to 5; Step 3: excavating a foundation trench at the pre-excavated position of the foundation pit to form the shape of the energy dissipation pool foundation pit; Step 4: After the stilling pool foundation pit is excavated and formed, concrete is poured in the foundation pit to form the stilling pool structure.

7. The method for deep foundation pit excavation under complex geological conditions according to claim 6, characterized in that: In step one, gravel material is laid on the surface layer of the construction area.

8. The method for deep foundation pit excavation under complex geological conditions according to claim 6, characterized in that: In step three, during the excavation process, water is drained openly, a collection well and a drainage ditch are set up in the foundation pit, and the water in the collection well is pumped out of the foundation pit by a water pump; the drainage ditch is excavated around or in the center of the bottom of the foundation pit, and multiple collection wells are set up in the foundation pit, and one end of the drainage ditch is led into the collection well.

9. The method for excavating a deep foundation pit under complex geological conditions according to claim 6, characterized in that: In step 2, when constructing the foundation piles, the effective elevation of the foundation piles is located below the surface layer of the construction area; The top of the top section of the steel cage of the foundation pile is fixed to the positioning baffle, and then the auxiliary device is hoisted downward as a whole, so that the top section of the steel cage is hoisted downward synchronously until the support plate is limited to the hole of the foundation pile. At this time, the hoisting of the steel cage of the foundation pile is completed; When pouring concrete into the pile hole of the foundation pile to the positioning baffle, stop pouring. The distance between the positioning baffle and the support plate is the empty pile part of the foundation pile.

10. The method for deep foundation pit excavation under complex geological conditions according to claim 6, characterized in that: In step 2, during the construction of retaining piles, an impact drill is used to drill holes and mud is used to protect the walls. Multiple retaining piles are constructed, and multiple retaining piles are arranged in a single row with a distance between adjacent retaining piles. A crown beam is constructed on the top of the retaining piles.

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