干热岩地热资源潜力巨大、绿色可再生，其开发和利用对我国具有战略意义，但总体上仍处于研发试验阶段。原因之一是深部高温高压条件下干热岩安全高效压裂还存在技术瓶颈。充分认识EGS（增强型地热系统）下井周和井间裂缝形成机制和规律是压裂技术突破的关键。然而缺乏EGS压裂原位模拟实验装置以及基于此的模型试验研究，严重制约了该技术的开发。本研究设计箍筒式高温高应力大试样原位压裂模拟装置，针对自主提出的干热岩井-缝联络型EGS系统，开展以下研究:（1）花岗岩高温准静态和变频拉剪破裂成缝规律;（2）原位条件下单井、多井变频压裂裂隙生成与贯联规律;（3）水/CO2（干冰）的低中频、高频脉冲、变频以及同步/异步压裂效应;（4）建立高温高应力花岗岩破裂和井间裂缝贯联的数学模型。研究成果将弥补高温及地层约束条件下大试样变频压裂实验和认识的缺乏，服务青海共和盆地等干热岩示范工程压裂设计。

Hot dry rock geothermal resource is one of the strategic energy because it is clean, renewable and has great potential of exploration in China. But in general, it is still in the R&D stage. One of the key reasons is that the technical bottleneck of safe and efficient fracturing and generation technology of geothermal reservoir in dense hot dry rock under deep high temperature and stress conditions needs to be broken through urgently. Fully understanding the formation mechanism of reservoir fractures around and between wells under specific EGS scheme is the premise and key to the breakthrough of fracturing technology. However, the lack of large-scale sample fracturing in-situ simulation platform for EGS and test studies based on it seriously restricts the development of this technology. In this study, a skillfully designed hoop-type in-situ fracturing simulation system for large specimens are developed as a tool, and an innovative umbrella-type EGS system will be proposed. Experimental and simulation approaches are used to study the fracture characteristics of granite under high temperature quasi-static and variable frequency tension-shear loading respectively. The fracture generation and connection characteristics of single well and multiple wells by variable frequency fracturing under simulated in-situ conditions. We will study the effects of water/CO2 (dry ice) fracturing at low to medium frequency,variable high frequency pulse and synchronous/asynchronous fracturings,respectively. We will establish mathematical models of tension-shear failure and fracture connection characteristics by comprehensive experiments, simulations and theoretical analysis. The research will fill in the knowledge blank of variable frequency fracturing of granite under in-situ temperature, stress constrained conditions of large samples, and provide valuable support to the hot dry rock demonstration projects such as Gonghe Basin in Qinghai Province.