The generalized plastic mechanics developed from the traditional plastic mechanics can reflect the real deformation mechanism of geomaterials. According to the generalized plastic mechanics，the constitutive model is composed of three plastic potential surfaces and three corresponding yield surfaces. The relationship between the yield surface and the plastic potential surface is discussed systematically，and the basic characters of yield surface，especially of volume yield surface that can calculate dilatant volume strain and shear yield surface in stress Lode angle direction，are also discussed.

The damage structure and constitutive relation of common bedded composite rock are researched. The micrcoscopic study of rock by SEM shows the characteristic of their microstructure and micropore. The damage constitutive equations and damage evolution equation in three dimensional nonlinear state are derived under different conditions，such as unequal biaxial stress，different effective stress，different mechanical parameters and damage evolution processes for every stratification. The study results are well testified by experiments.

The adhesion factors in adhesion model of rocks are changed with the non-linear relations through analyzing the mechanical experiment curves of rocks. Therefore，a new ahead model of rocks is proposed through the change：H-(H‖N)-(M‖St.V)，where M is a modified model about the I. Newton’s model. The model is of the feature of the non-linear accelerative creep of rocks.

The menace of delay outburst of coal and gas is very serious. The mechanism of delay outburst of coal and gas is studied with nonlinear theory，catastrophe theory，and some useful conclusions are drawn. It is concluded that the delay time of coal and gas delay outburst is obtained by the combination of geostresses，gas inside the coal，physico-mechanical characteristics of coal and external action，e.g. explosion. According to above research，the way to predict delay outburst of coal and gas is discussed.

Combined with the underground engineering practice in high geo-stress area，the stress restitution testing and lag monitoring are made to determine the induced stress field of surrounding rocks for underground engineering. The correctness of testing results is checked by elastic mechanics theory and individual hole stress rescission testing，and satisfying results are obtained.

The composed rock beam model for movement of overlying strata in stope is proposed. The key stratum of strata movement，the strata combinations of ground control and the separated bed are unified in this model，and a unitive criterion for determining the key stratum，the strata combinations and the separated bed is founded with an example analyzed. The applications of the composed rock beam model in ground control，surface subsidence control and gas prevention in coalmine are studied deeply. This model provides a unified idea and method for study of pressure in longwall mining and strata movement.

In view of the shortcomings of the simple genetic algorithm(SGA)，such as slow convergence and premature character，a new algorithm with fast convergence，good performance is proposed by improving the encoding，generation of initial population and genetic operators. And the new algorithm is tested and verified by experiments. An evolutionary neural network(ENN) model is constructed by using this algorithm to evolve the architecture and parameters of neural network. At last，the prediction on the thickness of the loosen zone around roadway is made with this ENN model，and the results show that the convergence and the forecasting capability are all good.

Through large-span physical simulation experiment for a road tunnel engineering under different surrounding rock mass conditions，the analysis is carried out on displacement and stability of surrounding rock mass of road tunnel. Then the construction of road tunnel is guided by this analysis.

Constitutive model is established to take the slide surface，tear or yield of the layer into account comprehensively. With this model，the safety factor of anchored rock masses is determined against integrate slide and compared with that obtained by limit equilibrium theory.

Based on the assumption of straight slip surface，a general expression of safety factor for step-shaped slope is deduced by using the traditional concept of safety factor. Since the deduced expression is analytical equation that is simple and easy to use，the effect of analysis and design of slope stability is improved .

a multi-functional anchor method，that is called self drilling-grouting anchor，is presented. The action mechanism of this method is analysed to grouting results for soil-reinforcement and preloading of anchor. With unique features of the presented method，it can be used to improve the soil strength，and increase the stability of slope during excavation.

The triaxial tests of Nanyang unsaturated expansive soil are carried out under four kinds of stress paths，that is isotropic loading tests at various controlled suction，shrinkage tests at various controlled net mean stress，swelling tests at various controlled net mean stress and drained shear tests under controlled cell pressure and suction. Many meaningfull results are obtained. The yield behaviour under isotropic loading of expansive soil can be described by the LC curve，The yield suction of shrinkage test decreases as the net mean stress increasing. The friction angle under unsaturated state is close to that under saturated condition. The total cohesion increases with suction. The water content changes linearly with the net mean stress at isotropic loading test and triaxial shear test. The relationship between water content and suction is also linear under shrinkage test and swelling test.

Based on the computer seeking，a new algorithm is proposed to calculate the reliability indexes of structures. This method avoids the disadvantages of traditional JC method and has no need to search for the derivatives of limit state functions. So it can be used widely in the reliability indexes of nonlinear limit state functions of structures.