"The primary objective of this project was to improve the LAMP code by adding transient and nonlinear analysis capability for investigation the thermo-mechanical responses associated with underground coal conversion (UCC). In particular, this study entailed (i) the determination of transient-nonlinear and steady-state temperature profiles from the energy balance equation for a selected cavity configuration and (ii) the evaluation of the associated displacements and stresses induced by thermal and in situ loading. A nonlinear constitutive law is used and interface elements are introduced for a more realistic modeling. This program supplements an ongoing contract with the Department of Energy which has the specific objectives of studying 2-D and 3-D subsidence histories, stable cavity configurations, thermal crack propagation, and design guidelines for UCC applications. Subsidiary objectives of this program included the transfer of technology to staff from Gulf R. and D. by means of frequent interaction and graduate student input. The computer program HEAT is written primarily for UCC applications. However, the program can be applied to various other problems such as steady-state or transient convective diffusion (or mass transport), potential flow, geothermal and any other thermal stress problems. This report outlines model formulations and numerical methods employed in the program HEAT. Input data preparations and formats are shown in detail. Various sample input data and results are provided also."