Expansive soil cement modifying and filling construction method

Abstract

An expansive soil cement modifying and filling construction method includes the following steps of (1) carrying out a modified material general characteristic test; (2) carrying out excavated material moisture content prompt drop and soil mass breaking construction; (3) carrying out broken soil moisture content and soil mass graded construction quality inspection; (4) carrying out cement mixing construction; (5) carrying out modified cement soil uniformity construction quality inspection; (6) carrying out modified cement soil grinding and filling construction; (7) carrying out modified cement soil filling construction quality inspection; (8) carrying out conventional maintenance. Different breaking construction methods are selected according to the measured natural moisture content omega o for soil mass breaking construction, the requirements for soil mass grades and moisture content of cement mixing uniformity can be met, cement is uniformly mixed at first and then 3-5 percent of water is supplemented in cement mixing and construction, it is guaranteed that the moisture content is approximate to the optimum moisture content during modified cement soil grinding and filling, meanwhile the requirement for time of modified cement soil grinding and filling construction is put forward, and modified cement soil filling quality is guaranteed.

Description

technical field [0001] The invention relates to the technical field of expansive soil treatment, in particular to an expansive soil cement modification and filling construction method. Background technique [0002] 1. Expansive soil engineering hazards [0003] my country is one of the countries with the widest distribution range and largest area of ​​expansive soil (rock) in the world. Since the 1950s, more than 20 provinces, municipalities, and autonomous regions have been found to be endangered by expansive soils in my country, covering almost all land except the South China Sea. same, but their shared expansion properties are the same. [0004] Expansive soil is a special soil that swells when exposed to water and shrinks when it loses water. It has many cracks, super-consolidation, disintegration, and weathering. Railways, highways, airports, water conservancy projects, etc. often suffer huge damage, causing significant economic losses. Therefore, to carry out engine...

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Problems solved by technology

[0011] 4. Construction problems of cement modified expansive soil

[0013] (1) The uniformity of cement modification: In order to ensure the effect of expansive soil cement modification, the mixing of cement and soil materials during construction should be fully uniform

The more uniform the mixing of cement and soil materials, the more fully the chemical reaction will occur, and the better the modification effect will be. If the mixing of cement is not uniform enough, it will inevitably cause the local ash dosage to be too low or too high, which will easily cause the modified soil to be affected by the atmosphere. Produce uneven expansion and contraction deformation

At present, there are two main factors that affect the uniform mixing of cement during construction: ① In expansive soil areas, the groundwater level is high, and the moisture content of excavated materials is often much higher than the plastic limit, so it is easy to aggregate and difficult to mix when mixed with cement; ② Expansion The soil is clay with high liquid limit, poor water permeability, easy compaction of soil clods, and there are a large number of super large soil cliques in the excavated material. During the process of cement mixing, cement cannot be mixed into the soil cliques.

In order to eliminate the above-mentioned unfavorable factors, the lower the moisture content of the excavated material during construction, the finer the soil mass is broken, the easier it is to mix cement evenly, but if it is too low and too fine, the construction cost and construction period will need to be doubled

[0014] (2) Construction problems of cement-modified soil filling: The construction of cement-modified soil filling is different from other conventional earthwork filling. If the cement-modified soil is left (or stuffed) for too long, it will affect the soil after rolling and filling. The main reason is that the gel substance attached to the surface of the particles produced by the cement hydration reaction will destroy the cementation of the soil particles during the compaction process, which is extremely unfavorable to the strength and compaction density of the improved soil.

In addition, when the cement-modified soil is mixed with ash and rolled into the filling process, the moisture content of the soil cannot be guaranteed due to the large amount of heat generated during the chemical reaction of the cement-soil, which accelerates the evaporation of water. Keep near the optimal moisture content

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