Determination of geomechanical properties and collapse potential of a caliche by in situ and laboratory tests
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- Zorlu, K. & Kasapoglu, K.E. Environ Geol (2009) 56: 1449. doi:10.1007/s00254-008-1239-7
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Working in complex grounds have always been difficult for engineering geologists because of the heterogenous nature of such geo-materials, which results in different behaviors under stresses. The caliches outcropping in the Adana basin and its close vicinity are selected as the study material because of their highly complex nature and also understanding their mechanical behaviour and collapse potential is too difficult, although their aerial extent is large in the region. For this reason, investigation of the collapse potential and mechanical behaviour of the caliches by applying new approaches besides the conventional in situ and laboratory tests is the purpose of the study. The study includes five main stages such as measurements of caliche profiles, in situ tests (plate loading), sampling, shooting photographs for photoanalyses and laboratory studies. Four different levels such as hard pan; silty, sandy layer; gravelly, blocky layer and clayey level are described for the caliches employed. The hard pan level is a weak rock with an average uniaxial compressive strength of 11.89 MPa while the others have typical soil characteristics. A series of plate loading tests are applied on the blocky, gravelly level of the caliche to determine the modulus of elasticity. The modulus of elasticity and the allowable bearing capacity are determined between 28.6–65.3 and 1.5–2.0 MPa, respectively. To determine the grain size distribution curve, in addition to sieve analyses, a photoanalysis technique is also applied and a combination procedure between the results from both sieve analyses and photoanalyses is introduced and the grain size curves for the blocky, gravelly level of the caliche are obtained. According to the results of collapse potential index tests performed on the samples collected from 20 locations of the study area, the soft pan level of the caliche has slight to moderate degree of collapse indices. In the final stage, various simple and statistically meaningful empirical equations are proposed for the indirect determination of the collapse index by employing simple paramateres.