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Abstract In order to control the soil disturbance caused by construction passing beneath highly dense building districts and to ensure the construction influence within small disturbance domain，the determination of indices for evaluating small disturbance and investigation on their variations under different stress paths during underground-crossing construction have become crucial issues. From the perspectives of stress disturbance and strain disturbance，the shear modulus，pore water pressure and critical stress state surface are chosen as main indices for small disturbance evaluation. The curves of modulus，pore pressure and stress vs. strain for undisturbed soil are obtained by laboratory tests to quantitatively analyze the changes in stress and strain under different stress paths induced by underground-crossing construction. The results indicate that the shear modulus decreases sharply as strain increases in a small strain domain，but the change ranges of shear modulus are different under different stress paths. Meanwhile，a slight change in strain may lead to an evident change in pore pressure. Moreover，according to the failure surface and the definition of disturbance ratio，a critical stress state surface may be specified for the control of small disturbance in underground-crossing construction.
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Received: 23 April 2010
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2011, Vol. 30 
