Variable dip fault slip simulation test method

A variable dip fault slip simulation test method, which adopts a sample device and a loading device;

• the sample device comprises a bottom plate, a sliding partition plate, a combined pressing plate and a rotating baffle;
• front and rear edges of the bottom plate are provided with sliding grooves, left and right sides of the bottom plate are provided with the sliding partition plates, front and rear ends of the the sliding partition plates are provided with sliding blocks, and the sliding blocks are slidably connected in the sliding grooves;
• the front and rear sides of the bottom plate are provided with the combined pressing plates, wherein the combined pressing plates are formed by splicing a plurality of the pressing blocks from head to tail, and two ends of the combined pressing plate are spliced with ends of the sliding partition plate;
• a rotating baffle is arranged at a middle position of the bottom plate, wherein the rotating baffle comprises a fixed plate and a sliding plate, the fixed plate is rotatably connected with the middle position of the bottom plate and the fixed plate is detachably connected with the bottom plate, and both sides of the fixed plate are slidably connected with a sliding plate;
• an end of the sliding plate is provided with a positioning member, wherein the positioning member is detachably connected with the combined pressing plate;
• the loading device comprises a loading support platform, a top loading indenter, a top pressure bearing unit, a bottom loading indenter, a side loading indenter, a side pressure bearing unit, a bearing seat, a strain gauge, an acoustic emission detector, a computer and a camera;
• the loading support platform comprises a base, a left loading support frame, a right loading support frame and an upper loading support frame;
• the left and right sides of the base are respectively provided with the left loading support frame and the right loading support frame, and the upper loading support frame is provided on the left loading support frame and the right loading support frame;
• a top loading indenter is arranged on the upper loading support frame;
• the top bearing unit comprises a force transfer column, a roller and an upper pressure bearing plate, an upper end of the force transfer column is connected with the top loading indenter, a lower end of the force transfer column is rotated side by side and is connected with a plurality of rollers, and one side of the upper pressure bearing plate is provided with a baffle bent downward;
• the bottom loading indenter is set on the base;
• the bearing seat is arranged on the left loading support frame, and a right end of the bearing seat is rotated side by side from top to bottom to connect a plurality of rollers;
• a side loading indenter is arranged on the right loading support frame;
• the side pressure bearing unit comprises a guide shaft, a linear bearing, a side pressure bearing plate and the rollers, the guide shaft is arranged on a right side of the base, the linear bearing is arranged on the guide shaft, the side pressure bearing plate is arranged on the linear bearing, and a left end of the side pressure bearing plate is rotated side by side from top to bottom to connect a plurality of rollers;
• the method comprises the following steps:
• step 1. sample preparation
• rotating the fixed plate to a preset angle to simulate the fault inclination with the preset angle, so as to make the sliding plate stretch out and draw back relative to the fixed plate;
• connecting the sliding plate with the combined pressing plate for positioning through the positioning member;
• wherein the bottom plate, the sliding partition plate and the combined pressing plate form a semi-enclosed cavity, and the rotating baffle separates the semi-enclosed cavity into two cavities;
• applying lubricating oil on an upper surface of the bottom plate, an inner wall of the sliding partition plate, an inner wall of the combined pressing plate, and a surface of the rotating baffle, injecting a first type of rock material into the two cavities, removing the rotating baffle and the bottom plate after the first type of rock material solidifies into a rock-like sample, removing the lubricating oil on the surface of the rock-like sample, and maintaining the rock-like sample;
• wherein, the first type of rock material injected into the two cavities is the same material or different materials;
• step 2. sample assembly
• defining the rock-like sample in the cavity behind the rotating baffle as a footwall sample, and defining the rock-like sample in the cavity in front of the rotating baffle as the hanging wall sample, and the footwall sample and the hanging wall sample together form the rock-like sample;
• an overlapping interface between the footwall sample and the hanging wall sample is a fault interface, placing the combined pressing plates on upper and lower sides of the rock-like samples, placing the sliding partition plates on left and right sides of rock-like samples, splicing the combined pressing plate with the the sliding partition plate, wherein the combined pressing plate is disconnected at the fault interface;
• step 3. loading preparation
• in the rock-like samples, placing the footwall sample at the lower left and the hanging wall sample at the upper right, wherein the combined pressing plate on the lower side of the footwall sample is attached to the bottom loading indenter, the sliding partition plate on the left side of the footwall sample is attached to a plurality of the rollers on the bearing seat;
• placing the top pressure bearing unit on the upper side of the hanging wall sample, wherein the combined pressing plate on the upper side of the hanging wall sample is attached to the upper pressure bearing plate, the top position of the sliding partition plate on the right side of the hanging wall sample is attached to the baffle, and the other positions except the top position of the sliding partition plate on the right side of the hanging wall sample are attached to the plurality of rollers on the side pressure bearing plate;
• or, in the rock-like samples, placing the footwall sample at the lower right and the hanging wall sample at the upper left;
• wherein the combined pressing plate on the lower side of the hanging wall sample is attached to the bottom loading indenter, and the sliding partition plate on the left side of the hanging wall sample is attached to the plurality of the rollers on the bearing seat;
• placing the top pressure bearing unit on the upper side of the footwall sample, wherein the combined pressing plate on the upper side of the footwall sample is attached to the upper pressure bearing plate, the top position of the sliding partition plate on the right side of the footwall sample is attached to the baffle, and the other positions except the top position of the sliding partition plate on the right side of the footwall sample are attached to the plurality of the rollers on the side pressure bearing plate;
• arranging the strain gauges along the fault interface on the surface of rock-like samples, arranging acoustic emission detectors on the left and right sides of the surface of rock-like samples, applying speckle on the surface of rock-like samples, aligning the camera with the surface of rock-like samples, connecting the top loading indenter, the bottom loading indenter, the side loading indenter, the strain gauges, the acoustic emission detectors and the camera with computer via signals, respectively;
• step 4. sample loading
• when “in the rock-like sample, placing the footwall sample at the lower left and the hanging wall sample at the upper right”,
• the computer first drives the side loading indenter to apply a lateral stress of the preset pressure to the rock-like sample, and then the computer drives the top loading indenter to apply an axial stress of the preset pressure to the rock-like sample;
• during the normal dip slip of the hanging wall sample relative to the footwall sample, the side pressure bearing plate moves horizontally to the right, the plurality of the rollers at the lower end of the force transfer column roll along the surface of the upper pressure bearing plate, and the plurality of the rollers at the left end of the side pressure bearing plate roll along the surface of the sliding partition plate on the right side of the hanging wall sample;
• when “in the rock-like sample, placing the footwall sample at the lower right and the hanging wall sample at the upper left”,
• the computer first drives the side loading indenter to apply a lateral stress of the preset pressure to the rock-like sample, and then the computer drives the bottom loading indenter to apply an axial stress of the preset pressure to the rock-like sample;
• during the reverse dip slip of the hanging wall sample relative to the footwall sample, the side pressure bearing plate moves horizontally to the left, the plurality of the rollers at the right end of the bearing seat roll along the surface of the sliding partition plate on the left side of the hanging wall sample;
• the plurality of the rollers at the lower end of the force transfer column roll along the surface of the upper pressure bearing plate, and the plurality of the rollers at the left end of the side pressure bearing plate roll along the surface of the sliding partition plate on the right side of the footwall sample;
• the computer records the real-time axial stress data of the top loading indenter, the real-time support pressure data of the bottom loading indenter, the real-time lateral stress data of the side loading indenter, the real-time strain data monitored by the strain gauge, the real-time acoustic emission data monitored by the acoustic emission detector and the real-time speckle change data monitored by the camera;
• after loading, removing the rock-like sample, observing and recording the failure of the fault interface on the surface of the rock-like sample.