The glider sustained substantial damage when it ground looped and skidded to a stop while landing at a grass airstrip. The pilot reported that after releasing from the tow airplane at 3,000 feet above ground level (agl), no thermal lift was encountered so he returned to the airstrip for landing. He reported that he experienced a sink rate that "seemed very excessive" during the downwind leg. He "cut the pattern short" and turned onto the base leg, which resulted in the glider being high on the base leg. The pilot reported that he deployed the spoilers, but he was slow to retract the spoilers due to the "heavy force required to push the handle forward." The glider lost altitude. The pilot reported that the left wing caught the grass about the same time the glider touched down with the nose about 20 degrees off the runway heading.