Drilling and grouting construction method for sand gravel stratum

Abstract

The invention belongs to the technical field of civil engineering, and relates to a drilling and grouting construction method for a sand gravel stratum. The drilling and grouting construction method for the sand gravel stratum comprises the following steps that firstly, hole drilling is carried out, and pipe following drilling is conducted for downward feeding of a wall protection casing pipe; secondly, a grout pipe line is downwards fed; thirdly, an orifice blocking device is installed; fourthly, according to grouting procedures, a proper water cement ratio is adopted for grouting and grout proportioning changing till grouting completion; and fifthly, grouting construction is carried out. The drilling and grouting construction method for the sand gravel stratum has the beneficial effectsthat the problems caused when a perforated pipe enters the sand gravel stratum are solved; the setting depth is controllable, and compared with an inserting and beating method, the drilling and grouting construction method is easy to conduct; the problem that in the process of pulling out the casing pipe, the sand gravel stratum collapses, and consequently the perforated pipe is blocked is prevented, and the problem that slip casting cannot be effectively conducted in the sand gravel stratum is solved; the installation and operation difficulty of a stop-grouting plug is lowered; the effect onthe grouting diffusion radius is relatively small; the process defects are overcome, and the grouting quality is reliable; and the drilling and grouting construction method is suitable for any sand gravel stratum, can be implemented without process tests and has very obvious beneficial effects for a region where the stratum is complex.

Description

technical field [0001] The invention belongs to the technical field of civil engineering, and relates to a drilling and grouting construction method for sand and gravel formations. Background technique [0002] 1 The main methods of drilling grouting in sand and gravel formations. At present, when grouting sand and gravel formations at home and abroad, the following methods are usually adopted: 1) Grouting with flower tubes; Bottom-up (top-down) segmental plugging grouting; 3) mud wall solidification, top-down segmental, orifice sealing grouting; 4) pre-embedded flower tube grouting, etc. [0003] 2 The main methods and principles of grouting construction in sand and gravel strata are as follows: [0004] 2.1 Grouting for flower tubes: [0005] Grouting with flower tubes is to drive the thick-walled seamless steel pipe with flower tubes directly into the irrigated stratum, and use it to directly connect to the grout delivery pipeline for grouting. The main construction met...

AI Technical Summary

Problems solved by technology

[0019] 3.1 There are limitations in the grouting of flower tubes. The thick-walled seamless steel pipes with flower tubes are used for grouting of flower tubes to directly drive into the ground to be irrigated, and a bottom-up method is adopted. After a section is filled, a section is pulled out. Casing, pouring the upper section, repeating the extubation and grouting until the grouting of the foundation of the gravel layer is completed

[0021] 2) When a large intubation force is adopted, it is easy to cause the flower tube to be broken and bent, and it is not suitable for the construction in the deep section of the sand and gravel stratum.

[0023] 4) In the process of flower tube insertion, when there are boulders and other large-sized gravels in the stratum, it is difficult to insert the flower tube to the designed position due to the obstruction of the stones at the bottom of the flower tube

[0024] 3.2 The grouting effect of the casing following up the retaining wall and segmental plugging affects the grouting effect in the stratum with a large fine particle content

However, this construction process requires the casing to be pulled up and left the grouting section before grouting can be carried out. If the hole collapses during the pulling out process, the slag collapsed in the hole will form a barrier and barrier, and the upper and lower boundary conditions of the grouting section will be different. For the same grouting segment, the lower half is affected by slag shielding, and the grouting quality is difficult to be guaranteed, especially when there is a lot of fine particles in the formation, the impact will be more serious

[0026] 3.3 Analysis of the existing problems of grouting with mud-solidified, segmented from top to bottom, orifice closed grouting: 1) Mud is used for wall-solidified drilling, and in the process of wall-solidified with clay slurry or the thinnest grade of cement-clay slurry, the mud flows into sand and gravel After the porosity, the groutability of the formation is changed, and the diffusion range of the grout is also reduced. The strength of the locally poured mud in the formation is not enough to meet the design requirements

2) The length of the grouting section is generally 1-3m, and the lower limit is 1m for the formation that is prone to collapse and serious leakage. If necessary, the section length is shortened to 0.5m, which increases the length of the grouting cycle section and lowers the construction efficiency.

[0028] 1) The drilling diameter is required to be 2-3 grades larger than the pre-embedded flower tube, that is, the drilling diameter is required to be more than 130-150mm, which increases the difficulty of drilling and drilling with the tube

[0029] 2) The process is relatively complicated. Drilling a thick-diameter flower tube and filling it is equivalent to the second hole-forming operation, and it is more difficult than the first hole-forming operation. First, it must be ensured that the hole wall will not collapse when the flower tube is built in, which is convenient Downpipe or filler; secondly, the sleeve valve should be made on the flower tube according to the "sleeve valve" grouting method, and the filler should be equipped with open-loop and shell-breaking filler. The filler should have low water separation, good stability, and small underwater condensation shrinkage , Early strength growth is fast, late strength growth is slow, stones are brittle, etc.

Therefore, in the actual sand and gravel grouting construction, seldom use

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