CN201713811U

CN201713811U - Stepped cone-shaped pile foundation applicable to karst regions

Info

Publication number: CN201713811U
Application number: CN2010201334878U
Authority: CN
Inventors: 付宏渊; 郭彤; 贺炜
Original assignee: Changsha University of Science and Technology
Current assignee: Changsha University of Science and Technology
Priority date: 2010-03-17
Filing date: 2010-03-17
Publication date: 2011-01-19
Anticipated expiration: 2020-03-17

Abstract

The utility model discloses a stepped cone-shaped pile foundation comprising a pile foundation body. The pile foundation body adopts a stepped cone-shaped pile (4); bearing surfaces (5) are formed on the steps of the stepped cone-shaped pile except for an end bearing surface (6); and a layer of bedding course (8) with different requirements for rigidity and thickness is constructed on each bearing surface (5). The pile foundation adopts the implementation method that a forming hole is excavated on a karst foundation, hole shrinkage treatment is conducted downwards at regular intervals from the earth surface to an end bearing surface (6) so as to form bearing surfaces (5) at different levels, and a layer of bedding course (8) with different requirements for rigidity and thickness is constructed on the bearing surface (5) at each level; and the setting principle is that the bedding courses on the lower bearing surfaces are in smaller thickness, while the bearing surfaces on the upper bearing surfaces are in larger thickness, then a corresponding reinforcing cage is placed into the pile hole, and finally, concrete is cast into the pile hole so as to form the stepped cone-shaped pile (4). The stepped cone-shaped pile provided by the utility model has larger bearing capacity and smaller settlement, and is applicable to karst regions.

Description

A kind of ladder taper pile foundation that is applicable to the karst region

Technical field

The utility model relates to a kind of stake side steps taper surface that passes through of karst region that is applicable to load progressively is passed to the pile foundation of ground on every side, down carry out undergauge by the face of land when refering in particular to pile every a segment distance, and on undergauges at different levels place's stake soil contact face, bed course is set, guarantee that ladder tapered pile each section side friction and end resistance are by the design idea performance, the pile top load classification is delivered in the ground, to guarantee engineering safety.

Background technology

During the pile foundation that constructs a bridge in the karst region, the karst of underground growth is built to engineering and is brought many difficulties, it is very complicated to reach a situation that the interior ground of the following certain limit of end contains solution cavity around many holes, as adopt traditional Pile Foundations Design, be difficult to guarantee that pile side friction or end resistance normally bring into play by design load.And the scheme that generally adopts at present is with the pile foundation lengthening, until stake being arranged on the complete basement rock, or directly designs according to friction pile.When adopting lengthening pile foundation scheme, the operation of ground deep is difficulty very, cost is significantly increased, and have the construction safety problem; And when adopting the friction pile scheme, a stake top displacement may be bigger, and it is subjected to the safety behind the dynamic load function also to be difficult to guarantee.The shape of stake if can be become the ladder taper, then can bring into play enough supporting forces on the taper surface, and pile foundation be up big and down small, avoid owing to end resistance inefficacy causes thrusting destruction.Like this, the pile foundation that can needn't extend simply, and can better guarantee engineering safety, and reduce unnecessary waste, still there is not this type of technology at present.

The utility model content

Technical problem to be solved in the utility model provides a kind of ladder taper pile foundation that is applicable to the karst region with bigger supporting capacity and less settling amount.

In order to solve the problems of the technologies described above, the ladder taper pile foundation that is applicable to the karst region that the utility model provides, comprise the pile foundation body, described pile foundation body is the ladder tapered pile, described ladder tapered pile is until the end bearing surface bearing surfaces that are formed with at different levels, and construction has one deck to have the bed course of different-stiffness and thickness requirement respectively on described bearing surfaces at different levels.

Be applicable to the job practices of the ladder taper pile foundation of karst region, on the karst ground, excavate pore-forming, down carrying out undergauge every a segment distance by the face of land handles, form bearing surfaces at different levels, until arriving the end bearing surface, the one deck of constructing respectively on bearing surfaces at different levels then has the bed course of different-stiffness and thickness requirement, its setting principle is that the bearing surface cushion thickness of bottom is little, the bearing surface cushion thickness on top is big, inserts the reinforcing cage that adapts with the stake hole again, and last placing of concrete forms the ladder tapered pile.

Adopt the ladder taper pile foundation that is applicable to the karst region of technique scheme, having overcome present karst region solution cavity grows very complicated, be difficult to guarantee pile side friction or end resistance problem when adopting conventional Pile Foundations Design by the normal performance of design load, the ladder tapered pile that the utility model provides, down carry out undergauge by the face of land during pile every a segment distance, and on undergauges at different levels place's stake soil contact face, certain thickness bed course is set, guarantee that each section side friction and end resistance bring into play by design idea, can reach the pile top load classification is passed to purpose in the ground, have bigger supporting capacity and less settling amount to guarantee the basis.The implementation method of the utility model patent is: adopt hand excavation's method pore-forming on the karst ground, carry out undergauge every a segment distance and handle, finish until excavation.Behind every grade of undergauge face filing, the certain thickness bed course of constructing, every grade of undergauge face cushion thickness is advisable to guarantee pile foundation collateral resistance and the normal performance of end resistance below this grade undergauge face.After pile foundation was subjected to vertical uniform load q, pile side frictions at different levels are performance earlier, and end resistance at different levels performance step by step from lower to upper, treat each bed course displacement value of reaching capacity after, pile foundation end resistances at different levels are brought into play gradually fully, the bearing capacity of pile foundation value of reaching capacity.

Description of drawings

Fig. 1 is each ingredient schematic diagram of ladder tapered pile;

Fig. 2 is a ladder tapered pile carrying schematic diagram;

Fig. 3 is the enlarged drawing at A place among Fig. 2.

The specific embodiment

With reference to figure 1, Fig. 2 and Fig. 3, ladder tapered pile 4 is until end bearing surface 6 bearing surfaces 5 that are formed with at different levels, and construction has one deck to have the bed course 8 of different-stiffness and thickness requirement respectively on bearing surfaces 5 at different levels.The karst ground is by last overburden layer 1, solution cavity 3 in rock 2 and the ground is formed, the job practices of ladder tapered pile 4 is: excavate pore-forming on the karst ground, down carrying out undergauge every a segment distance by the face of land handles, bearing surfaces 5 at different levels will be formed behind every grade of undergauge face filing, until arriving end bearing surface 6, the one deck of constructing respectively on bearing surfaces 5 at different levels then has the bed course 8 of different-stiffness and thickness requirement, its setting principle is that the bearing surface cushion thickness of bottom is little, the bearing surface cushion thickness on top is big, insert the reinforcing cage that adapts with the stake hole again, last placing of concrete forms ladder tapered pile 4.

With reference to figure 1, Fig. 2 and Fig. 3, when being subjected to pile top load 10, stake does the time spent, because bed course 8 initial stiffnesses on the bearing surfaces 5 at different levels are less, pile cutoff pile side resistances 7 at different levels are at first all brought into play, this moment, bearing surfaces 5 at different levels and end bearing surface 6 performance drag proportions were less.Increase along with pile top load 10, adapt to the big and little characteristics of end displacement of pile foundation top displacement, bed course with different-stiffness and thickness requirement design guarantees bearing surfaces 5 at different levels and holds supporting capacity 9 limiting values on the bearing surface 6 to bring into play fully simultaneously that pile foundation reaches the bearing capacity limiting value.

Claims

1. ladder taper pile foundation that is applicable to the karst region, comprise the pile foundation body, it is characterized in that: described pile foundation body is ladder tapered pile (4), described ladder tapered pile (4) is until end bearing surface (6) bearing surfaces (5) that are formed with at different levels, and construction has one deck to have the bed course (8) of different-stiffness and thickness requirement respectively on described bearing surfaces at different levels (5).