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The Research on the Swelling Deformation Law of Expansive Rock (Soil) in Luwangfen for the Midline of North Water Transfer Project

Author: DongXiaoJuan
Tutor: XiangWei
School: China University of Geosciences
Course: Geological Engineering
Keywords: Remolded expansive rock ( soil ) Swelling and shrinkage deformation Initial state Cycle progression Modification of
CLC: P642.1
Type: Master's thesis
Year: 2010
Downloads: 135
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Abstract

Expansion of water swelling, dehydration contraction characteristics geotechnical engineering buildings bring great harm, not only affect the stability of the slope, embankment, pavement of roads, railways, channels, and undermine building foundations, resulting in superstructure cracking, and expansive soft rock tunnel surrounding rock lining structure, or even damage the stability of the the tunnel internal support structure, and so on. Expansion geotechnical studies, regardless of the macroscopic deformation or micro have quite a lot of research. However, by its structure due to the expansion of the engineering properties of soils and rocks a great influence, different regions, different causes expansion geotechnical its swelling characteristics very different, even opposite conclusion, therefore there is a need for a different region of the expansion geotechnical study. North Water Transfer Project Lu Wang grave test segment swelling rock (soil) is half rock and half soil state, not fully weathered another close to completely weathered state, the state shall be rocky, dry conditions and very hard, once the water will quickly soften the soil referred to here as the swelling rock (soil). Disturbed slopes during the excavation process, a certain depth of the channels surface swelling rock (soil), we need them rolling, then this part of the expansion of the rock (soil) will have similar remolded expansion characteristics. In this paper, the results of previous studies, mainly from the expansion, contraction and expansion and contraction cycle three aspects remolded expansive rock (soil), the expansion and contraction of the deformation characteristics and the modification of the part of the RCC samples obtained The following results provide some theoretical basis for the design and construction of the channel slope. This paper first analyzes the basic physical and chemical properties of the test section swelling rock (soil), come to the expansion of rock (soil) as a the weak expansion viscous geotechnical main minerals kaolinite, there is a small amount of smectite and illite and other minerals, its weak expansion provides the basic material foundation; simultaneous determination of the optimum water content of swelling rock (soil), maximum dry density, provide basic control indicators for the expansion and contraction of the back test. On this basis, the paper analyzes the relationship remolded expansive rock (soil) without charge inflated initial state of deformation of the specimen obtained unconfined remolded expansive rock (soil) without charge expansion deformation and initial moisture content linearly decreasing relationship, and the greater the initial dry bulk density, expansion rate decreasing rate increases with the increase in the initial moisture content no charge; swelling deformation without charge the same with the initial stem density reduction decreases were the polyline curve relationship, and by the maximum dry density starts to decrease, No Charge expansion coefficient of a large rate of decrease, when the degree of compaction is less than 96%, no the Dutch expansion coefficient changes rapidly slowed and stabilized. Also analyzed whether the unconfined expansion deformation remolded expansive rock (soil) without charge to draw larger level because no side limited sample deformation, and to sample soil particles in the deformation process continue to fall off, a lot of space for the subsequent expansion deformation, lead to the expansion and deformation of the sample in the unconfined case the amount is significantly less than the amount of deformation the unconfined case of expansion, and its size is less than half of the unconfined conditions. Engineering practice, most of the expansion of Geotechnical by the overlying load. This paper also analyzes the relationship remodeling swelling rock (soil) initial state of charge expansion deformation of the specimen, and the following conclusions: When the initial dry density is relatively small, the overlying load greater than the expansion stress, remodeling swelling rock (soil) flooding does not swell, but a collapsible, and with the overlying load increases, the collapsible amount of deformation first increases and then decreases, appears the collapsible peak; initial dry density of compaction degree more than 96%, remolded expansive rock (soil) always showed swelling deformation after flooding in the overlying loads its charge expansion deformation with the upper cover the load decreases with an increase and eventually tends to a stable value, in engineering practice, dealing with expansion geotechnical problems, especially weak expansion geotechnical, we have to consider the size of the overlying load judge expansion geotechnical flooding expansion or not the additional load, and then take the right approach. The greater the initial moisture content of sample particles to complete the expansion of larger deformation in this preparation process, the same volume of sample porosity than the smaller hydrophobic channel blocked, so the Dutch expansion deformation with the initial moisture content increases; For the small initial dry density of the sample, the overlying load is relatively large, the sample collapsible deformation occurs, the deformation amount of size also decreases with increasing initial moisture and showed a line sexual variation. On this basis, this paper suitable for dry density is relatively large remodeling kind of charge expansion deformation and the initial moisture content and the overlying loads relationship formula. This article is also found in the remodeling samples have charge expansion deformation, limit the expansion of the test section swelling rock (soil) moisture content by its initial moisture content did not affect hardly changes as the overlying load on inflation limit of the impact is relatively large, the greater the overlying load, the greater the effective stress in the sample, the smaller the suction of the sample of water, resulting in the smaller the swelling limit water content, when suction is no longer affected by the load to a certain extent its impact, swelling limit tends to a certain value. In addition, the article also devoted to an analysis of the relationship between the water content of Dutch expansion process, pointed out that the sample moisture content increases the absorption of the same moisture content as its expansion deformation increments are getting smaller and smaller, to achieve the inflation limit swelling deformation is also terminated. Many studies have pointed out that the expansion force decreases with increasing initial moisture paper remolded expansive rock (soil) expansion force by different initial state determination, but reached a different conclusion, namely the expansion force with the initial moisture content the increase of the rate first increases and then decreases, indicating the size of the expansion stress is not only related to the initial state of the specimen, with a lot of changes in the pore structure of the sample during the test. Also studied the shrinkage deformation characteristics of of remolded expansive rock (soil), draw the amount of shrinkage deformation increases with the increase of the initial moisture content; shrinkage limit also increases with the increase of the initial moisture content, and the initial moisture content rate close liquid limit shrinkage limit tends to be stable, and no longer increases with the rate of increase of the initial water, which also verified measured shrinkage limit the method of the geotextile specification. In addition, the article also remolded expansive rock (soil) cycle of expansion and contraction deformation characteristics, show that the the deformation with increased cycle progression and reduce expansion and contraction and swelling characteristics reduce quickly reaches a certain level cycle progression The expansion and contraction of the sample deformation stabilized changed little with increasing series. Therefore, the pre-swelling rock (soil) occurrence of multi-stage cycle of expansion and contraction deformation, but also reduce the swelling characteristics. This paper presents a new improved expansion geotechnical above remolded expansive rock (soil) is based on the expansion and contraction of the study of the deformation law that use ion the soil enhancer ISS improved expansion geotechnical. The studies have shown that the ISS improvement remodeling and expansion of rock (soil), the expansion and contraction of the performance is well improved significantly reduced; shear strength has also been greatly improved. In the expansive test compared on the basis of this paper, the ISS improved test section of remolded expansive rock (soil) best solution ratio of 1:300 (volume ratio).

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CLC: > Astronomy,Earth Sciences > Geology > Hydrogeology and Engineering Geology > Engineering Geology > Soil science
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