岩石脆延转化力学行为规律是深部岩石力学研究的重要内容之一，同时也是影响深地工程安全高效实施的关键因素。为研究深部不同深度岩石脆延转化力学行为差异性规律，以松辽盆地1000 m~6400 m不同赋存深度的砂岩、砾岩和安山岩为研究对象，开展了同一深度岩石不同应力水平下、不同深度岩石同一应力水平下以及不同深度岩石原位应力水平下的常规三轴实验，并采用峰前和峰后脆性指标分析了岩石的脆性特征，初步揭示了深部不同深度岩石脆延转化力学行为的关键影响因素与差异性规律。研究结果表明：不同深度岩石脆延转化并是非瞬时的，而是存在一个脆延性逐渐转换的应力区间。同一深度岩石不同应力水平下其脆延特征主要受围压影响。对于1600 m深砂岩，其脆性整体上随着围压的增大而减小，出现了从脆性—延性—应变硬化的转变，并且其峰后塑性逐渐增强，直到峰后呈现完全塑性。50 MPa~70 MPa应力水平范围为1600 m深砂岩的脆延转化区间；相同围压下不同深度岩石的脆延特征主要受其本身矿物组分的影响。对于松辽盆地岩石样品，其硬相矿物和中等相矿物的含量总体上随着深度的增加而增大，导致其脆性随深度的增加而增大，由浅至深表现出延性—脆延转化—脆性的特征；不同深度岩石原位应力水平下其峰后特征随着深度的增加呈现出不同的特征：1000 m~3500 m深砂岩表现出峰后应变软化特征、4800 m深砂岩和5100 m~5600 m深砾岩表现出峰后脆性特征、6400 m以深的安山岩表现出峰后塑性流动特征。岩石的脆延特征受诸多因素的影响，其中岩石的矿物组分和应力环境对其脆延特征的影响存在博弈现象。随着深度的增加硬相矿物和中等相矿物含量的增加会导致岩石的脆性增长，而岩石加载应力水平的增加，又会抑制岩石的脆性增长。研究结果有望指导深地科学探索及深地工程高效实施。

The mechanical behavior of brittle ductile transition in rocks is one of the essential components of deep rock mechanics,as well as a key factor that impacts the safe and efficient implementation of deep rock engineering projects.To study the differences in the mechanical behaviors of brittle ductile transition in deep rocks,the sandstones,conglomerates and andesites at different occurrence depths (1 000-6 400 m) from the Songliao Basin are taken as research objects,and a number of conventional triaxial tests are carried out on rocks at an identical depth but under different stress levels,rocks at different depths but under an identical stress level,and rocks under different stress levels and at different depths.The brittleness characteristics of rocks are analyzed by using the pre peak and the postpeak brittleness index.A preliminary understanding of the key influencing factors and differences in the mechanical behaviors of brittle ductile transition in deep rocks at different depths has been achieved.The research results show that rather than an instantaneous brittle ductile transition in rocks at different depths,a stress zone exists in progressive transition from brittleness to ductility.The brittleness of rocks at an identical depth but under different stress levels are mainly affected by the confining pressure.For sandstones at a depth of 1 600 m,its brittleness generally decreases with the increase of confining pressure,and there is a transition from its brittleness,ductility to strain hardening,its post peak plasticity gradually increases until it shows a complete plasticity after the peak.The stress level range of 50 MPa to 70 MPa is the brittle ductile transition zone of sandstones at the depth of 1 600 m.The brittle ductility characteristics of rocks at different depths under the same confining pressure are mainly affected by their own mineral components.For the rock samples from the Songliao Basin,their content of hard phase minerals and middle phase minerals generally increase with the increase of depths,which causes their brittleness to go up with depth increases,exhibiting a shallow to deep characteristic of transition from brittleness to ductility to brittleness.The post peak characteristics of in situ rock stress levels at different depths show different characteristics as the depth increases: the sandstones at depths from 1 000 m to 3 500 m depth show post peak straining softening,post peak brittleness is found in sandstones at the depth of 4 800 m and conglomerates from depths at 5 100 m to 5 600 m,while the andesites at the depth of 6 400 m manifest the characteristic of post peak plastic flow.Many factors affect the brittleness and ductility of rocks.Among them,game phenomenon exists in the impact on the brittleness and ductility of rocks between the mineral composition and stress environment.As the depth increases,the increase of hard phase minerals and middle phase minerals will cause the brittleness to increase,and the increase in the loading stress level will inhibit the brittleness of the rocks.The research results are expected to guide the scientific explorations and efficient implementation of the deep rock engineering.