Abstract：Integrity of rockmass has two parts of meanings，i.e. rockmass cutoff degree and rockmass fragmentation degree. Discontinuity length and spacing should be considered both in describing rockmass integrity，rather than the latter only. Rockmass cutoff degree and rockmass fragmentation degree are studied using spatial block identification technique. The results show that the greater the ratio of trace length to spacing of discontinuity is，the higher the cutoff degree is and the lower the integrity is. When the ratio of trace length to spacing is 3–4，the rockmass is divided into relatively discrete rockmass，which corresponds to comparative cracked one，i.e. the transition stage of complete to fractured rockmass，accordingly the rockmass structure type is inferior blocky. The rockmass fragmentation degree is not only dependent on discontinuity spacing，but also relevant to the ratio of trace length to spacing. When the rockmass is cut as block entirely，the fragmentation degree is controlled by spacing mainly. These conclusions can be used as supplementary conditions in classification of rockmass integrity and rockmass structure type. Furthermore，based on the conclusions drawn above，the influence of different distribution types of trace lengths with lognormal distribution is discussed. At last，the rockmass integrity and structure type of typical engineering are analyzed according to discontinuity statistic data. The research ways and the conclusions are of importance to further study of rockmass integrity.
