CN-121976517-A - Fiber reinforcement-negative pressure drainage composite foundation structure and construction method

Abstract

The invention relates to a fiber reinforcement-negative pressure drainage composite foundation structure and a construction method thereof. The structure comprises a negative pressure drainage layer and a fiber reinforced clay layer from bottom to top. The fiber reinforced clay layer is formed by uniformly mixing powdery clay and fibers and is used as a sealing layer and a preloading layer. The negative pressure drainage grating extends upwards and is partially embedded into the fiber reinforced clay layer, so that the two layers form a whole body with negative pressure drainage communication. During construction, the negative pressure drainage grating is paved, fiber reinforced clay is filled in layers, the upper end of the grating is embedded, and finally, a vacuum pump is connected for vacuumizing to carry out combined drainage consolidation. The structure can accelerate the drainage consolidation of the soft soil foundation, save the cost by utilizing local soil materials, strengthen the integrity and the crack resistance by fiber reinforcement, omit a special sealing film and simplify the construction.

Inventors

• LIN YANZI
• CHEN CI
• CHEN YANXING
• CHEN LINGZHI
• XU JIAMIN
• XIAO DENGFENG
• XIAO YONGJIE
• LIN FANGYI
• LIAO YANFENG
• CHEN YI
• ZHENG YUFAN
• XIAO HAN
• CHEN FUDONG

Assignees

• 福建省建筑设计研究院有限公司

Dates

Publication Date

20260505

Application Date

20260210

Claims (6)

1. 1. The utility model provides a fibre adds muscle-negative pressure drainage composite foundation structure which characterized in that includes from bottom to top sets gradually: a negative pressure drainage layer (8), wherein a negative pressure drainage grating is paved on the soft soil foundation, and the negative pressure drainage and consolidation treatment of the soft soil foundation are carried out through the negative pressure drainage grating; the fiber reinforced clay layer (9) is arranged above the negative pressure drainage layer (8) and is formed by uniformly mixing powdery clay and fibers; the negative pressure drainage grating extends upwards and is partially laid in the fiber reinforced clay layer (9), so that the negative pressure drainage layer (8) and the fiber reinforced clay layer (9) form an integral structure of negative pressure drainage communication through the negative pressure drainage grating, and the fiber reinforced clay layer (9) is used as a sealing layer and a preloading layer at the same time.
2. 2. The composite foundation structure according to claim 1, characterized in that the fibres are polypropylene fibres, the amount of which in the fibre reinforced clay layer (9) is 0.3-0.5% of the dry mass of powdery clay, the length being 8-10mm.
3. 3. The composite foundation structure of claim 2, wherein the optimal doping amount of the fibers is 0.4% and the optimal length is 9mm.
4. 4. The composite foundation structure according to claim 1, wherein the negative pressure drainage grating comprises grating plates (11) which are arranged in a net shape and have a certain height, transverse negative pressure pipes (12) which are arranged on the side wall grating plates (11) and are consistent with the extending direction of the grating plates (11), and vertical negative pressure pipes (13) which are arranged at the intersection of the grating plates (11), the vertical negative pressure pipes (13) and the transverse negative pressure pipes (12) are mutually communicated, the upper end and the lower end of each vertical negative pressure pipe (13) are blocked, and a plurality of exhaust holes (14) are uniformly distributed on the pipe wall.
5. 5. The composite foundation structure according to claim 4, characterized in that the upper and lower edges of the grating plates (11) are provided with upper and lower wing plates (111, 112), respectively, such that the cross section of the grating plates is i-shaped.
6. 6. A method of constructing a fiber reinforced negative pressure drainage composite foundation structure according to any one of claims 1 to 5, comprising the steps of: s1, field leveling, namely performing primary treatment on a soft soil foundation; s2, paving a negative pressure drainage grid on the soft soil substrate to form a negative pressure drainage layer (8); s3, uniformly mixing locally obtained powdery clay with fibers with preset doping amount and length to prepare fiber reinforced clay; s4, filling the fiber reinforced clay prepared in the step S3 on the negative pressure drainage layer (8) in a layered manner, and burying the upper end part of the negative pressure drainage grid into the fiber reinforced clay layer (9) in the filling process to form the fiber reinforced clay layer (9); S5, connecting the negative pressure drainage grid extension part to a vacuum pump, starting vacuumizing, forming negative pressure in the negative pressure drainage layer (8) and the fiber reinforced clay layer (9), and carrying out joint drainage consolidation; and S6, finishing construction after the foundation subsides stably.

Description

Fiber reinforcement-negative pressure drainage composite foundation structure and construction method Technical Field The invention relates to the technical field of civil engineering foundation treatment, in particular to a fiber reinforced negative pressure drainage composite foundation structure suitable for a powdery clay foundation with high water content and low strength in an eastern coastal area and a construction method thereof. Background In eastern coastal areas, soft or silty clay layers with high water content, high compressibility and low shear strength are widely distributed. The foundation has poor bearing capacity, large and uneven settlement after construction, is easy to generate cracks, and seriously affects the safety and stability of an upper roadbed or a building. In order to solve the problem, the prior art mainly adopts two types of processes for foundation reinforcement: One is the fiber reinforced soil technology. According to the technology, a certain proportion of fiber materials (such as polypropylene fibers) are doped in the soil body, and the lateral deformation of the soil body is restrained by utilizing the interfacial friction force between the fibers and soil particles and a three-dimensional space network formed by the fibers in the soil body, so that the tensile strength and the integrity of the soil body are improved, and the generation and the development of cracks are restrained. However, simple fiber reinforcement has limited effectiveness on soft foundations with high water content and high pore water pressure. One of the root causes of insufficient soil strength also comprises that the excessive water in the soil cannot be discharged out quickly, so that the effective stress is slowly increased. The soil drainage consolidation process can not be effectively accelerated only by fiber reinforcement, and the foundation bearing capacity is difficult to be greatly improved in a short time. In addition, the performance of the fiber reinforced soil is extremely sensitive to parameters such as the fiber doping amount and the fiber length, and incorrect parameter selection (such as too high doping amount) can even cause strength reduction, so that the clear optimization design parameters for the powdery clay in a composite stress state are lacking at present. And the second is a negative pressure drainage (vacuum preloading) technology. According to the technology, the drain board or the sand cushion layer is arranged in the soft soil foundation and is covered with the sealing film, negative pressure is formed in the foundation by utilizing the vacuum pump to suck air, pore water is accelerated to drain, soil consolidation is promoted, and therefore the foundation strength is improved rapidly. However, the conventional vacuum preloading method has the obvious disadvantages that firstly, a special sealing film is required to be paved to maintain a negative pressure environment, the material cost and construction complexity are increased, the sealing film is easy to damage and the vacuum degree is influenced to maintain, secondly, in order to achieve a better preloading effect, sometimes, the sealing film is required to be piled up, the construction steps and the cost are further increased, and finally, the method mainly treats deep soft soil, and the problem that the integral cooperative reinforcement of a filling layer or an improved layer with a certain thickness at the upper part is insufficient, so that the upper filling layer possibly becomes a new weak link due to insufficient strength is solved. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a fiber reinforcement-negative pressure drainage composite foundation structure and a construction method thereof. The structure can effectively accelerate the drainage consolidation of the soft soil foundation, fully utilize local soil materials, enhance the integrity and crack resistance of the foundation, omit a special sealing film, simplify the construction and reduce the cost. In order to achieve the above purpose, the invention adopts the following technical scheme: The method comprises the following steps of: The negative pressure drainage layer is paved with a negative pressure drainage grating on the soft soil foundation, and the negative pressure drainage and consolidation treatment of the soft soil foundation is carried out through the negative pressure drainage grating; the fiber reinforced clay layer is arranged on the negative pressure drainage layer and is formed by uniformly mixing powdery clay and fibers; The negative pressure drainage grating extends upwards and is partially laid in the fiber reinforced clay layer, so that the negative pressure drainage layer and the fiber reinforced clay layer form an integral structure of negative pressure drainage communication through the negative pressure drainage grating, and the fiber reinforced clay layer is simultaneous